1999 Chevrolet Silverado 5.7 L 4x4
150k miles

Problem: Wont Start, truck is broken down in a parking lot 5 miles from my house in jeporady of being towed.

Symptoms:

As I turn the key, it sounds like it might start for a 1/4 second, but then just cranks and cranks.

Supporting Information:

I can hear the fuel pump comming on as I turn the key on. If I bypass the fuel pump relay, It comes on and stays on and I can hear fuel in the injection tubes, but it still will not start.

It has a full tank of gas.

I have already replaced the fuel pump once, not sure how long ago, but it seems to be working.

Battery is good.

The idiot lights show a battery symbol and check engine soon is lit.

Next Move:

1.) I am going to check fuel pressure if I can get a guage.

2.) I am going to check for spark.

3.) I am going to try to get the trouble codes read out if i can get my hands on a meter.

Question:

Anyone have any other ideas of what I can do short of the items that require a special meter/guage that I listed above?

Should I replace the fuel filter just incase?

Thanks!

If you purchased bad gas or have over 30,000 mile on it change the filter or if you can blow through the filter it will run the truck. A bad pressure regulator the pressure will come up and go down. Try using a hose clamp on the return line on a section of rubber hose. If it starts drive home and change the pressure regulator.
If you belong to AAA have it towed home where you have tools and ect.

Could you elaborate on clamping the return line? Im not sure I know what line to clamp. I thought the lines were metal...

I think I may just put a new filter and regulator on and hope for the best, but I am willing to try this test you mentioned.

Thanks much, really.

Could you elaborate on clamping the return line? Im not sure I know what line to clamp. I thought the lines were metal...

I think I may just put a new filter and regulator on and hope for the best, but I am willing to try this test you mentioned.

Thanks much, really.

Please read MT-2500's post in this thread http://www.automotiveforums.com/vbulletin/showthread.php?t=633914

Since you have a no start condition, first thing is to find out if you are at the necessary 60-65 PSI to start and go from there.

//2000CAYukon

Mine has done a similiar thing. I'll turn the key and it will sound like it's going to start...I actually hear my exhaust fire up. Then dies. It has something to do with my Security. When this happens my security light flashes. I know I should fix it, but opening my door, closing it, then turning the key again fixes it. I'd rather do this than pay the dealer an arm and a leg just to look at it.

Ok Folks, Here is whats going on with the beast,

I checked the fuel pressure. When I turn the key on and the pump comes on it reads 55-57 PSI.

From other posts, and the shop manual, this appears to be too low. SO, I replaced the fuel filter and nothing changed.

What next? Fuel pressure regulator?

Fuel pump?

I read the computer and there were no codes. However, I had the computer unplugged at some point during all this so it may have reset.

Thanks for any pointers you can give.

The spec for fuel pressure is 55 to 65 so you appear good. Does the pressure drop after the initial pressure. If the regulator is bad it will come up then drop when vacuum gets to it. Is their gas in the vacuum line to the regulator.

No, there is not gas in the vac line. I am not sure about the pressure drop. I did not test the pressure with the fuel pump forced on. I only watched it when I turned the key and the pump ran for 5 seconds. It appears to be steady for the 5 seconds, and then when it stops, it does drop down several psi, not sure how much.

Is there a way to test the regulator?

Thanks for the help!

Ok Folks, Here is whats going on with the beast,

I checked the fuel pressure. When I turn the key on and the pump comes on it reads 55-57 PSI.

From other posts, and the shop manual, this appears to be too low. SO, I replaced the fuel filter and nothing changed.

What next? Fuel pressure regulator?

Fuel pump?

I read the computer and there were no codes. However, I had the computer unplugged at some point during all this so it may have reset.

Thanks for any pointers you can give.

55/57 will not fire a injector on a cold start.
You need at least 63/64 or more.

If you have good fire try a little carb cleaner in the intake or pinch off furl return line and see if pressure will come up some.

Here is guide lines on fuel pressure.
With a no start check as much as you can on it.
Hard to start cold.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.
Post back fuel pressure readings.

MT-2500 is correct about the specs.but unless his gage is dead weight pressure tested every 10 days it is probably off + or - 5 psi. I used to do nuclear shop inspection and every new pressure gage was dead weight tested before use. I bought a new set of MAC gages,hoses and every one was bad and leaked.
While you are cranking the pressure should stay up or the regulator is bad.
If the pump shuts off while cranking you are losing reference pulse. After you replace a regulator they should be adjusted by using a torx screwdriver in the end to the proper pressure. Either buy a gage or borrow one. You have been over a week on this. You also could have a bad o-ring leaking on the regulator bleeding off pressure.

Ok, now were gettin somewhere. The manual did say that the reading should be around 66, so since it is only 55 or so, maybe that is it. But if the guage is off, it could be at 60 or so, still less than the manual says it should be.

I will do a pressure test while cranking and get back to you.

THANK YOU!

All,

I tested the fuel pressure while I was cranking and it held steady at 55psi. After I stopped cranking it did gradually go down. Over about 15 minutes it dropped to about 30psi or so. Should it stay steady at 55psi after I stop cranking?

The first time I tried to start it it actually ran for a split second. I could hear the exhaust, etc.

I may still replace the fuel pressure regulator if it is fairly cheap. It seems I definitely have a fuel problem.

If that does not work then I guess it is the Pump? Or maybe just the sender?

I could not figure out how to pinch off the return fuel line. The lines are all hard sleeve.

Would you recommend somehow attaching a temporary rubber hose to the return line and dumping it in a can or something and pinching it off?

If so, what would that tell me?

On another note, related to the post about guage accuracy, Even if my guage was off 5 psi, my pressure would still be low. Maybe it is off 10 though? Maybe I should get a new guage.

Hmmmmmm

Thanks.

55 is to low you need a good 63-65 lbs cold cranking.
The leak down is not bad. Just watch for a real fast leak down.
like 10-20 lbs a minute
If you can not pinch return line off either take off and plug the end of it or just go to the fuel filter line from the pump and hook onto it and check direct full fuel pump pressure.
Should be 75-85 lbs.
And also make sure the pump is getting good voltage and ground.
On the gauge you could try it on another car/truck or try another gauge.
Good luck
MT

My 2000 silverado has two disconnects at the fuel rail by the regulator. I use a k-d tool to disconnect these type fittings. My wifes malibu uses this type of fitting on one end of the filter. These would readidly available at a yard. You could cut off a section and put a bolt in the end and make a test tool. The filter end looks to be almost exactly 5/16 inch you could buy a 6 inch piece of fuel injection hose put a bolt in it and use two clamps to block the line for a test. I was going to check on a filter but I only had spares for my truck as I recently changed it. Check a piece of hose on a filter before purchasing it.
Your gage may be 5 psi low so judge according to at least MT-2500 test pressure. The tool looks like two bars with a piece of tubing for 5/16 and 3/8 fittings. They used to be around $6.00 although they make plastic ones also.
Mine is a 5.3L but yours surely has flexible with disconnects. One line is metallic cable and the other is gasline material with a plastic cover.If the truck starts during the test you are sure you have low pressure.

All,

Ok, I went ahead and replaced the fuel pressure regulator. It did not help. Waste of 50 bucks. Oh well.

I called the dealer and they said that 55psi is fine for the fuel pressure. They said that they think it is related to the security system and that there may have been a technical service bullitin on it a while back....

I think I may be barking up the wrong tree with this fuel pressure thing.

more later

All,

Ok, I went ahead and replaced the fuel pressure regulator. It did not help. Waste of 50 bucks. Oh well.

I called the dealer and they said that 55psi is fine for the fuel pressure. They said that they think it is related to the security system and that there may have been a technical service bullitin on it a while back....

I think I may be barking up the wrong tree with this fuel pressure thing.

more later

O boy.
To put it blunty if a dealer told you 55 lbs of fuel pressure is enough he does not know his rear end from a hole in the ground. :grinyes: :grinno: :lol:

The injectors have to have 64-65 lbs of fuel pressure on a cold start.
After a COLD START IT MAY RUN ALL DAY ON 55 LBS OF PRESSURE BUT IT WILL NOT COLD START.
You can not leave home without it.

Find another dealer fast.

Run the complet fuel pressure test as posted.
And post back results.

A simple test is to shoot just a little carb cleaner / no starting fluid in the intake and see if it will start.

If the security system is the problem it will start for 30 seconds and then shut down.
MT.

All,

I have been working on the truck all day,

I tried putting fuel additive in the tank to dry the fuel incase of water contamination. No dice.

I tried putting starting fluid into the intake. It will run on that if I keep spraying it of course.

The fuel pressure is still 55psi and does not leak down after I turn the key off.

The dealer says 55 is OK, but the shop manual says it should be 60 - 66 psi.

Unless anyone else has an idea, I guess I will go ahead and replace the fuel pump I guess.

The only other thing I can do is try to measure the pressure right out of the pump, but I need a special adapter for that.....

HELP, I am close to throwing in the towel and having it towed to the dealer.

Thanks for all the help thus far.

MT-2500,

I tried to follow your post as best I could, I may have read it wrong.

I measured the cold fuel pressure and it was 55.

I measured the pressure when it was cranking and it was 55.

I cannot measure it when it is running obviously.

I replaced the fuel regulator so I assumed that would negate the need to do the return line fuel pinch thing.

I am thinking that it is the pump, what do you think?

Did I miss something in your post?

Thanks!!!!

I would use a line block it is a block of metal with a 1/8 inch bar bent to a L shape. I would clamp down on the rubber return line watching the pressure until I got 65 psi if it starts you are certain it is a fuel problem. Then I would shut down and pinch closed the rubber return line. Check the pressure if low buy a new pump. I saw on ebay a new delco for 110.00 which is cheaper than the dealer. If you don't have a floor jack pull tail light wires "disconnect". Unscrew fuel line at fill door. Unbolt bed get two men to help pick up bed and move to back of truck. Use a brass drift and loosen hold down after fuel lines are disconnected. remove pump install new pump and sock. Get truck running if no leaks reinstall bed.
Use a flashlight and find two flexable lines on back of engine. The metal clad will be high pressure. The rubber line with plastic cover will be return hose.
Check out today get pump fedx overnight. and go

MT-2500,

I tried to follow your post as best I could, I may have read it wrong.

I measured the cold fuel pressure and it was 55.

I measured the pressure when it was cranking and it was 55.

I cannot measure it when it is running obviously.

I replaced the fuel regulator so I assumed that would negate the need to do the return line fuel pinch thing.

I am thinking that it is the pump, what do you think?

Did I miss something in your post?

Thanks!!!!

The true test on a fuel pump is with return line pinched off or pluged or you can disconect the fuel filter check direct fuel pressure at fuel filter inlet line.
If the fuel pump does not put out 75-85 full pressure then replace it.
MT

The point of what he is saying is you may have two bad regulators check the pump before you spend your money and don't accomplish any thing. It would have been much easier to check the pump than to replace a regulator that was probably good. It would have saved you fifty dollars which could been used for a pump if needed. Also if the new regulator is bad you could get replaced free if the pump passes the pressure test. They just don't replace parts unless you can prove it is bad.
Once you decide to test it will be done in a short time it is not difficult. Four ways were explained to you.

Do you have an extra key? I believe that you may have a transponder in the key . I've had 3 of them go bad on me in 3 other cars. It's an easy thing to check for. Just get your other key & see if she starts.

My 2000 silverado has two disconnects at the fuel rail by the regulator. I use a k-d tool to disconnect these type fittings. My wifes malibu uses this type of fitting on one end of the filter. These would readidly available at a yard. You could cut off a section and put a bolt in the end and make a test tool. The filter end looks to be almost exactly 5/16 inch you could buy a 6 inch piece of fuel injection hose put a bolt in it and use two clamps to block the line for a test. I was going to check on a filter but I only had spares for my truck as I recently changed it. Check a piece of hose on a filter before purchasing it.
Your gage may be 5 psi low so judge according to at least MT-2500 test pressure. The tool looks like two bars with a piece of tubing for 5/16 and 3/8 fittings. They used to be around $6.00 although they make plastic ones also.
Mine is a 5.3L but yours surely has flexible with disconnects. One line is metallic cable and the other is gasline material with a plastic cover.If the truck starts during the test you are sure you have low pressure.

Which one of those lines by the regulator is the supply? The bottom one?

The true test on a fuel pump is with return line pinched off or pluged or you can disconect the fuel filter check direct fuel pressure at fuel filter inlet line.
If the fuel pump does not put out 75-85 full pressure then replace it.
MT

Ok, I am convinced to test with the return pinched. I bought a couple of small sections of hose to put on the return line. I just am confused on which one is the return. Is it the bottom one?

Also, once I get the hose on the return, I assume I should put the end in a jar or something to catch the fuel and then just pinch the hose until I get 65psi.

What does this do? Does this produce more pressure in the manifold than normal? If it starts then that means that my pump is bad?

I will try the test soon.

Thanks for the patience.

On my truck it is the bottom line. The top has metallic covering so it would the high pressure. The rubber line goes to the gas tank. I would slide back the plastic and pinch it down. If you are doing this no need to disconnect. I would pinch down until your gage reads over 60psi. Then I would try to start. If it starts shut it off and pinch down all the way. Since your pump is working it apparently has a dirty sock or is getting worn out.
The only reason for trying to start it for proving to yourself the pressure is the problem. This way you will know if its the pump or two bad regulators. A badly bent line from a stone will cause lack of flow and even though it has pressure the bleed will drop it the pressure below what you need.

Ok, I am convinced to test with the return pinched. I bought a couple of small sections of hose to put on the return line. I just am confused on which one is the return. Is it the bottom one?

Also, once I get the hose on the return, I assume I should put the end in a jar or something to catch the fuel and then just pinch the hose until I get 65psi.

What does this do? Does this produce more pressure in the manifold than normal? If it starts then that means that my pump is bad?

I will try the test soon.

Thanks for the patience.

If you are having problems with pinching off the reture line.:grinyes: :lol:
Just remove the inlet line from the fuel filter and hook your gauge direct on to it.
Post back the pressure you get there.

All,

Ok, I tested the pressure with the return line pinched off. It made no difference. It still would not start and still would not go over about 55psi.

I also tried a different ignition key for grins.

I suppose the final test would be to test the pressure right out of the pump where it goes into the filter, I just need to figure out how to adapt the line to my guage.

I will try to work that out and report back.

Also, my old regulator had an adjustment screw on it, but the new one does not. Not sure why.

Anyway, let me know if this helps you to help me any.

Thanks.

If you had it completely pinched off the next step is a new pump. If you want to check at the filter go to a hardware store with a filter and get connections to screw your gage into.

All,

I worked on the truck some more today,

1.) I took the bed off the truck to get at the pump. I put a T on the send line and put the guage on it and clamped the exit side. It measured 90psi.

I am not sure if this is a valid test though, since one side was clamped. I was not able to put it in line due to the fact that I could not adapt to the line. I tried to put it inline in place of the filter, but also could not adapt to the guage there.

Is it valid to test the way i did?

If it is, then that would suggest there is something wrong in the line somewhere..... I inspected the line, and it is well protected, very unlikely a stone would have hit it. I did not see anything obvious.

I did purchase a new pump, but I do not want to put it in if the one I have is not bad. It was EXPENSIVE.

ANY IDEAS?

Oh by the way, the dealer said that it should run on 55psi, and that that issue with the injectors not firing was related to another engine and does not apply to mine. However, the manual still says it should be 65.

I also attempted to reset the security system per the dealer by turning the key on but not starting the engine for 15 min, then off then on for 15 min, then off then on for 15 min.

No dice.

2.) I also tried to just put the guage inline right at the pump. I took a short hose from the send line, through the T and then right back into the pump return. That did not seem to work very well, it only measured about 10psi.

HELP! Now I have my cap and bed taking up another whole parking space! AHHHHHRGGHHHH....

Oh, I pulled the pump and looked at the strainer, it looked ok to me....nothing obvious wrong in the tank..

If you have the k-d disconnect tool I would remove the 4 short lines that attach to the fuel tank and fuel rail. Only try one at a time so they don't get mixed up and do the supply first. I would suspect if one suffered from internal collapse it would be the metallic cloth covered one the inlet as you pinched off the return. You could also blow through it with an air hose.They are short enough that you should be able to see through it. I have had brake hoses collapse internally and you couldn't bleed them.
I would suspect your gage is reading slightly high 5 or 10lbs. I would check to see if you can blow through the fuel filter. I would also check the directional arrow to be sure it isn't installed backwards. I would do this first.
You are learning alot so it isn't a loss by any means. You could pinch off the return line by the tank and retest. If this works try the origional regulator and by an adjustment tool and try to adjust. Mine uses a T-10 tamper proof torx.

All,

I worked on the truck some more today,

1.) I took the bed off the truck to get at the pump. I put a T on the send line and put the guage on it and clamped the exit side. It measured 90psi.

I am not sure if this is a valid test though, since one side was clamped. I was not able to put it in line due to the fact that I could not adapt to the line. I tried to put it inline in place of the filter, but also could not adapt to the guage there.

Is it valid to test the way i did?

If it is, then that would suggest there is something wrong in the line somewhere..... I inspected the line, and it is well protected, very unlikely a stone would have hit it. I did not see anything obvious.

I did purchase a new pump, but I do not want to put it in if the one I have is not bad. It was EXPENSIVE.

ANY IDEAS?

Oh by the way, the dealer said that it should run on 55psi, and that that issue with the injectors not firing was related to another engine and does not apply to mine. However, the manual still says it should be 65.

I also attempted to reset the security system per the dealer by turning the key on but not starting the engine for 15 min, then off then on for 15 min, then off then on for 15 min.

No dice.

2.) I also tried to just put the guage inline right at the pump. I took a short hose from the send line, through the T and then right back into the pump return. That did not seem to work very well, it only measured about 10psi.

HELP! Now I have my cap and bed taking up another whole parking space! AHHHHHRGGHHHH....


One more time.
I assume you can still start and run it.
Here is the proper procedure for checking the fuel pump and pressure.
Make sure your gauge is correct and acurate. 2-3 lbs off will mess up testing.
Proper testing is the only way you are going to know what is bad on it.
Good Luck
MT

Hard to start cold.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.
Post back fuel pressure readings.

One more time.
I assume you can still start and run it.
Here is the proper procedure for checking the fuel pump and pressure.
Make sure your gauge is correct and acurate. 2-3 lbs off will mess up testing.
Proper testing is the only way you are going to know what is bad on it.
Good Luck
MT

Hard to start cold.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.
Post back fuel pressure readings.


Can you tell me did I perform the test at the pump correctly? I took a piece of hose from the send port on the pump to a T and then the other side of the T to a piece of hose that was clamped off. The top of the T went to the guage. It read 90psi. Is that a valid test or does the guage have to be inline?

It seems if it read 90psi the pump is good and it would point to a bad fuel line somewhere.....

Can you tell me did I perform the test at the pump correctly? I took a piece of hose from the send port on the pump to a T and then the other side of the T to a piece of hose that was clamped off. The top of the T went to the guage. It read 90psi. Is that a valid test or does the guage have to be inline?

It seems if it read 90psi the pump is good and it would point to a bad fuel line somewhere.....

Kinda of a round about way but a good test on full pressure.
But was the fuel pump hot after running on road or just a cold One shot test?
But you also need to go threw the other test I posted.
Fuel pumps can fail cold or hot or just get weak after running.
Or can be losing pressure at fuel regulater or injector body.
You need to threw the complete test to find out if pump or other stuff is the problem.
Good Luck

Kinda of a round about way but a good test on full pressure.
But was the fuel pump hot after running on road or just a cold One shot test?
But you also need to go threw the other test I posted.
Fuel pumps can fail cold or hot or just get weak after running.
Or can be losing pressure at fuel regulater or injector body.
You need to threw the complete test to find out if pump or other stuff is the problem.
Good Luck

No, the pump was not hot. The truck will not run. It has been broken down for several weeks in a parking lot.
I tested the pressure by turning the key on and watching the guage.
What other test did you mention? I tested at the manifold, 55psi. I tested with the return clamped, 55psi. I tested while cranking, 55psi. I tested at the pump, 90psi. I am attempting to test inline in place of the fuel filter.

I replaced the regulator and the filter.

Thanks again.

All,

Ok I give up. I am going to have it towed to the dealer.

I put my guage on a friends 04 tahoe and it read 55psi with the key on, and then about 40 psi while running.

Since his truck runs fine, I think my 55psi is fine.

I think I have wasted a bunch of time chasing down a fuel problem when it seems now like it might be a sensor or computer issue.

Thanks for all the help. I will post back the results.

Stop and think you said the truck ran when you sprayed starting fluid in it.
This means you have spark.
You said it tried to start when cranking this means you are getting power to the injectors.
You said you had 55psi at the fuel rail with the return pinched off.
You said you had 90psi at the pump with the return pinched off.
If you said 60psi water at the kitchen sink and 20psi in the bathroom your wife would say you had a problem. The engine is telling you that it has a problem.
Fram had a recall on filters for your truck. I asked you to check for proper flow direction fram stamps an out on the side with the flange. This is the engine side. I also asked you to blow through it if it has a problem you can't do this. I also told you how to check inlet hoses to the rail.
At least pinch off the return at the tank and retest. If you get 90psi unpinch to you get 65 and try to start.
If you go to the dealer you will pay triple what you paid for the pump a new filter and new hoses.
Also your gage is way out of calibration if it was just purchased new ask for a new gage. It took you 4 days to pinch off a hose but you got the bed off in a day so you must have mechanical ability. Just use your head and think what you are doing. The big thing is to have confidence you can do it which if you quit you will never get.

Stop and think you said the truck ran when you sprayed starting fluid in it.
This means you have spark.
You said it tried to start when cranking this means you are getting power to the injectors.
You said you had 55psi at the fuel rail with the return pinched off.
You said you had 90psi at the pump with the return pinched off.
If you said 60psi water at the kitchen sink and 20psi in the bathroom your wife would say you had a problem. The engine is telling you that it has a problem.
Fram had a recall on filters for your truck. I asked you to check for proper flow direction fram stamps an out on the side with the flange. This is the engine side. I also asked you to blow through it if it has a problem you can't do this. I also told you how to check inlet hoses to the rail.
At least pinch off the return at the tank and retest. If you get 90psi unpinch to you get 65 and try to start.
If you go to the dealer you will pay triple what you paid for the pump a new filter and new hoses.
Also your gage is way out of calibration if it was just purchased new ask for a new gage. It took you 4 days to pinch off a hose but you got the bed off in a day so you must have mechanical ability. Just use your head and think what you are doing. The big thing is to have confidence you can do it which if you quit you will never get.

1.) I checked the filter and the out is indeed toward the engine.

2.) I will blow through it, even though it is brand new and passing fuel and there is plenty of pressure at the rail, which is the same as another vehicle that runs fine.

3.) Why do you think the guage is out of calibration?

4.) The 90psi from the pump was to a dead head right at the pump. It did not go all the way to the engine, it was not an inline test. I have not been able to find fittings and hoses to adapt to the ones on the truck to allow an inline test. I could try to pinch the return at the pump, but I already did that right at the engine, and the pressure did not increase. So why would it help to do the same test again by pinching off at the pump this time?

This would all be much easier if the truck was at my residence which it is not. It is not in a well lit shop with all my tools. Blah Blah Blah.

I may give it another day or two of testing. I dont think I have a fuel supply problem though.

The shop manual says to:

1.) Check the Fuel injector coils

2.) Spark plugs

3.) EGR valve

4.) Ignition control circuit

5.) Restricted exhaust

6.) Throttle postion sensor

FYI

Thanks!

All,

Ok I give up. I am going to have it towed to the dealer.

I put my guage on a friends 04 tahoe and it read 55psi with the key on, and then about 40 psi while running.

Since his truck runs fine, I think my 55psi is fine.

I think I have wasted a bunch of time chasing down a fuel problem when it seems now like it might be a sensor or computer issue.

Thanks for all the help. I will post back the results.

You are welcome.
You have not wasted your time.
You gave it your best shot and done what you could.
From what you told us you have a fuel problem.
Your friends Tahoe may be a different set up on fuel pressure.
You have to have the 65 lbs lbs of pressure at injectors for your truck to start cold.

Good luck and
Let us know how it goes.

No, the pump was not hot. The truck will not run. It has been broken down for several weeks in a parking lot.
I tested the pressure by turning the key on and watching the guage.
What other test did you mention? I tested at the manifold, 55psi. I tested with the return clamped, 55psi. I tested while cranking, 55psi. I tested at the pump, 90psi. I am attempting to test inline in place of the fuel filter.

I replaced the regulator and the filter.

Thanks again.


If the pump is putting out 90 lbs of pressure and you only have 55 at injector rail/test port.
It is losing 35 lbs of pressure some place.
Is it holding a steady 55 at test port.
If so it is bypassing the fuel pressure regulator.
90 lbs at pump and with return line pinched off you should have 90 lbs at fuel rail test port.
If not that is your problem.
55 lbs of pressure will not start it.
A good pressure regulator will hold the pressure back at 65 lbs.

Do a retest and make sure you have the return line pinched off or blocked off.
Post back the pressure with return line pinched off or blocked off.
Then if fuel pressure does not come up retest the fuel pump direct pressure.
It may not be putting out full pressure all of the time.

You didn't say if you had a fram filter. Blue bowtie posted a recall for this type of filter. It apparently isn't machined correctly at the thread area and leaks this could be your problem. Wrap the filter with a dry towel if it is wet from gas this is your problem.
If the pump put out 90psi at the fuel tank it should have had within 1psi of this or at least 89psi at the fuel rail. Pressure doesn't drop that fast as no metal is bent it has to be (the filter)( a hose coming apart inside )( dirt in the fuel rail.)This assumes both tests were done correctly. (In fact basic electrical courses teach this as an example.)
Pressure is like electricity if you have 12volt at the battery you should have 12volt at the starter. If you only have 8volt the starter doesn't work correctly.
When you started with starting fluid you ruled out almost all of the manuals checks. Also when it tried to start it shows power to the injectors. Apparently the low fuel pressure causes a lean fuel mixture and you don't fire. Like the old choke that added extra fuel to start. This is why you need extra fuel pressure to start.This is why at idle the pressure drops and goes up when the engine is loaded. Vacuum is high at idle and drops as the engine speed picks up.

Ok,

I will retest with return blocked. I think I can block it back at the pump, or right at the fuel rail, however, I think that I previously tried to get that connection off and I could not, I think I may need a special tool for that.

The thing is that I am not seeing any fuel leaks around the filter or anywhere along the lines. There is one place up front where they bend to go up to the engine. They turn into rubber or something flexible for about 6 inches there and those connections are corroded on the outside. No suprise there.

How about this. What if I buy a 12 or 15 foot section of rubber hose and run it all the way from the pump, outside the truck to the fuel rail? That would test the whole line right? Maybe a long way around but at this point I have no idea where a possible blockage might be.

I do not have a fram filter I dont think, but I cannot really recall what brand it was. It was not in an orange FRAM box though...

More later, If it stops raining I will try to do more tests tonight.

Once again though, do you know if it is valid to test pump pressure to a dead head or do I have to be inline??????

Thx

Ok,

I will retest with return blocked. I think I can block it back at the pump, or right at the fuel rail, however, I think that I previously tried to get that connection off and I could not, I think I may need a special tool for that.

The thing is that I am not seeing any fuel leaks around the filter or anywhere along the lines. There is one place up front where they bend to go up to the engine. They turn into rubber or something flexible for about 6 inches there and those connections are corroded on the outside. No suprise there.

How about this. What if I buy a 12 or 15 foot section of rubber hose and run it all the way from the pump, outside the truck to the fuel rail? That would test the whole line right? Maybe a long way around but at this point I have no idea where a possible blockage might be.

I do not have a fram filter I dont think, but I cannot really recall what brand it was. It was not in an orange FRAM box though...

More later, If it stops raining I will try to do more tests tonight.

Once again though, do you know if it is valid to test pump pressure to a dead head or do I have to be inline??????

Thx


The best place to pinch the return line is at the engine and frame where the rubber part is.
Pinch it off and give us a reading on fuel pressure.

If you had 90psi at the pump discharge tube at top fitting coming out of the tank you should have had at least 89psi at the fuel rail test. If you use gas hose designed for this pressure it would be a valid test. If you disconnect the metal clad line and hook up your gage at this point it would be much cheaper.
I found a filter with a quick disconnect and you could disconnect the bottom rubber hose and use a piece of 5/16 fuel hose pushed on and clamped with a bolt in the end also clamped to the rail. Try to control costs and complete the test.
If I didn't think you had 90psi I would have told you to install a new pump which you purchased.

Alright guys we are getting WAY off base on this one.
First off look at this.
Turn ON the ignition leaving the engine OFF, the fuel pressure should be 415-455 kPa (60-66 psi) when the pump is running
If you do not have this pressure, the engine WILL NOT start. The reason is this engine has a poppet type injection system and if the pressure is not within specs, the ball will not be forced off the seat and fuel will not enter the engine.

The test you are performing by dead heading the pump is NOT A VALID TEST!
If the poppets are stuck closed, fuel will not enter the engine no matter what fuel pressure you have.
There is a procedure to unstuck the poppets available at your GM dealer..have your dealer reference TSB 00-06-04-003B

Ok,

Now I understand what you are trying to tell me. I sat down and actually read the shop manual more carefully.

I was reading the wrong fuel system diagnosis page. I was reading the page for the 4.3 L engine. The fuel pressure there said it should be 60 to 66psi, while the page for the 4.8, 5.3 and 6.0L engines said it should be 55 to 62psi.

SO! Maybe I never told you guys what engine I had. Sorry. I have a 5.3 L.

Therefore, the 55psi I have is fine. The test with the Tahoe confirms that.

However, the manual also said that the pressure should not leak down more than 5psi in 10 minutes. I am not exactly sure, I will test again, but I think it did leak down faster.

Therefore, my problem should be one of a few things,

1.) I have a bad fuel pump check valve

2.) I hae a bad fuel pump flex pipe

3.) The fuel pressure regulator is bad

Or

4.) I have a bad or leaking fuel injector.

SO, What do you think about THAT.:naughty:

I plan to do the following,

The book describes putting a fuel pipe shut off adapter inline between the fuel rail and the return line and feed line. Then, they walk through pressureizing the system and then turning off one valve then the other, effectively what you guys were trying to get me to do.

If the pressure remains constant on either test it points you to a leak in the regulator or injectors or in the fuel pump/line.

I may try to get some of these shut off valves, but first I will do the return block test and see if the pressure holds.

My problem is adapting to these screwy connections they use nowadays. It used to be all rubber hoses...

So my theory is that it is pumping up to the required 55psi, but may be immediately leaking down causing the split second start and then stall condition.

I dont suspect an injector though, it seems like that is unlikely.

Whew...

:banghead: :banghead: :banghead: :banghead: :banghead:
You told us it was a 5.7:banghead: :banghead: :banghead: :banghead:

Have you taken a fuel sample? You could have contaminated gas causing this...you didn't fill the tank with E85 did you?:nono:

Fuel pressure should not leak down..with all the work you have done, just pull up the fuel rail and see if you have any injectors leaking when you turn the key on and pressurize the rail.

:banghead: :banghead: :banghead: :banghead: :banghead:
You told us it was a 5.7:banghead: :banghead: :banghead: :banghead:

Have you taken a fuel sample? You could have contaminated gas causing this...you didn't fill the tank with E85 did you?:nono:

Fuel pressure should not leak down..with all the work you have done, just pull up the fuel rail and see if you have any injectors leaking when you turn the key on and pressurize the rail.

Sorry to all for the misinfo on the engine size. I did say 5.7, but it is a 5.3. My bad.

This did happen right after I got a full tank of gas. I tried putting gas dry stuff in the tank to see if that would help.

What is E85?

The gas smells really weird....

Sorry again.

Sorry to all for the misinfo on the engine size. I did say 5.7, but it is a 5.3. My bad.

This did happen right after I got a full tank of gas. I tried putting gas dry stuff in the tank to see if that would help.

What is E85?

The gas smells really weird....

Sorry again.

Well we all do things like that. :grinyes: :grinno: :lol:
Fuel specs for it is 55/62 and should hold at least 26 lbs after one minute of shut off.
55 is still a little low but a 5.3 should start.
Does it have 55 when cranking or just key on?
I would still do the pinch off return line fuel pressure check.
If pressure comes up with return line pinched try to start it with pressure up.
Is your security light going out or staying on?
Have you got a theft alarm or remote start on it.
If you have fuel pressure and good spark to all plugs then check for injector pulse.
All gas smells strange to me anymore.
If the gas smells strange get a second opinion like have someone else smell it that knows what gas should smell like.
Good luck
MT

Well we all do things like that. :grinyes: :grinno: :lol:
Fuel specs for it is 55/62 and should hold at least 26 lbs after one minute of shut off.
55 is still a little low but a 5.3 should start.
Does it have 55 when cranking or just key on?
I would still do the pinch off return line fuel pressure check.
If pressure comes up with return line pinched try to start it with pressure up.
Is your security light going out or staying on?
Have you got a theft alarm or remote start on it.
If you have fuel pressure and good spark to all plugs then check for injector pulse.
Good luck
MT

It has 55psi key on or cranking or with the return pinched off.

So I will do the return pinch thing again, but I did already do it. Even if I did not get it completely closed, it seems like it would have raised the pressure a bit.

My security light is not on, except when the door is open.
I have a battery light and service engine light on.
No codes readout on the code reader.
I have no theft or remote starter type devices on it.

I only checked one plug for spark, I will check all.

Thx

He said he did this test and had 55psi. He is checking pump pressure and said he had 90psi. He clamped the return line at the rail and still had 55psi. The question is what happened to the pressure.

He said he did this test and had 55psi. He is checking pump pressure and said he had 90psi. He clamped the return line at the rail and still had 55psi. The question is what happened to the pressure.


Very good question.
It is going to give me nightmares thinking about it.:grinyes: :grinno: :lol:
If the return line is pinched good and fuel pump is stiill puting out 90 lbs.
It should have 90 lbs at fuel rail.
Are you sure you are clamping the return line?
Double check your fuel pump out put.
Any gas in the vacume line to fuel pressure regulator or leaks at fuel rail?
Check more than one plug for good fire.
And get a noid light and check for injector pulse while cranking.

I looked over the posts again and since your engine has adequate pressure to start. As it wasn't a 5.7L but a 5.3L and it ran on starting fluid and your friend has a Tahoe. I would ask him if he would let you swap his pcm relay for a test also check the two 15amp injector fuses. The fuses are in the relay center. A print is on top of the cover. The relays are around $55.00 so this would be a big help.
Hopefully you are already running.

Thanks to all for the help. The truck is being towed to the dealer today. I really need it and cannot wait any longer.

I went ahead and put a new fuel pump in it, but it did not help.

If I turned on the key and let the fuel pressure build up to 55psi, and then clamped the fuel supply line, the pressure would hold. However, if I did not clamp anything the pressure dropped ~20psi in 10 min. The book said if it drops 5psi in 10 min you have a problem. The book recommended replacing the pump if it held with the supply pinched.

Anyway, I am going to cut my losses.

Again Thanks for the help. I will post the results of the dealers work.

Best regards.

Good luck to you.. hopefully they will not screw you too bad at the stealership

Thanks to all for the help. The truck is being towed to the dealer today. I really need it and cannot wait any longer.

I went ahead and put a new fuel pump in it, but it did not help.

If I turned on the key and let the fuel pressure build up to 55psi, and then clamped the fuel supply line, the pressure would hold. However, if I did not clamp anything the pressure dropped ~20psi in 10 min. The book said if it drops 5psi in 10 min you have a problem. The book recommended replacing the pump if it held with the supply pinched.

Anyway, I am going to cut my losses.

Again Thanks for the help. I will post the results of the dealers work.

Best regards.

You are welcome And.
Thanks for letting us know how it is going.
That fuel pressure is kinda of a brain tester.
Did the pressure ever go over 55 lbs.
Good Luck.
Let us know what the dealer finds.
MT

Hopefully the dealer will be able to fix it for a reasonable price. Do you live in a high salt area where you could have a pinhole in the gas line? I never was able to figure out your tests and this could explain the reason why.

I inspected the whole line and did not see any wet areas ever. I do not live in a high salt area really, the lines looked good from the outside except in one place where they transition to flex line as it goes up from the frame to the engine. However, no wetness there.

The tow truck guy was convinced it was the mass air flow sensor..but I disconnected that and it still would not start....

You cannot believe the number of opinions I have gotten while it has been sitting in the parking lot for the last several weeks.....

Anyway...I will let you know how big a loan I have to take out...I have already bought a new jar of vaseline....

Is the dealer still working on your truck. I was curious as to what they replaced?

There was a snafu with the dealer and the tow truck. The tow truck driver forgot to tell them that he dropped the truck off and where he put it. I had called to let them know it was comming, but they did not get the hint. Therefore, from a friday to the next monday I thought they were working on it and they did not even know it was there!

In addition, they were so busy, they did not even look at it until today.

They dont know what is wrong with it. They said it might be a PCM problem.

They said that the tech was on with the "techline help" or something like that.

This sounds like it is going to be expensive. If it is the PCM that is simple to replace, they better not charge me much for labor on that. I am sure the part is going to be expensive though.

I will let you know.

Thanks for keeping in touch.

I would ask for all defective parts as you can look over the job in your spare time.

Thanks for keeping in touch.

Thanks for the update. WE all want to know what is going on.

All,

The dealer called today with the bad news. Apparently there has been a "short" in the door lock sensor and door lock module which caused the PCM to think there was some safety/security issue and keep the engine from starting. They are putting in a new sensor, and module, and fixing any damaged wiring and reprogramming the PCM security stuff.

I know that is not much detail, and I may have the terminology off but that was all I could get over the phone. I will elaborate more once I pick up the truck and get the final rundown. Bottom line was it was an electrical failure that caused the computer to not let the truck start.

Cost, 1200.00.

Not to mention the 400 I threw away on the pump I did not need.

I am going to try to find out the steps they took and the tools they used to diagnose the problem. I will try to get the bad parts.

I suppose that I could have saved some money by just having them do the troubleshooting. I could have went down there in the parking lot and replaced the stuff they said was bad....

Anyway, more later once I get it back.

All,

The dealer called today with the bad news. Apparently there has been a "short" in the door lock sensor and door lock module which caused the PCM to think there was some safety/security issue and keep the engine from starting. They are putting in a new sensor, and module, and fixing any damaged wiring and reprogramming the PCM security stuff.

I know that is not much detail, and I may have the terminology off but that was all I could get over the phone. I will elaborate more once I pick up the truck and get the final rundown. Bottom line was it was an electrical failure that caused the computer to not let the truck start.

Cost, 1200.00.

Not to mention the 400 I threw away on the pump I did not need.

I am going to try to find out the steps they took and the tools they used to diagnose the problem. I will try to get the bad parts.

I suppose that I could have saved some money by just having them do the troubleshooting. I could have went down there in the parking lot and replaced the stuff they said was bad....

Anyway, more later once I get it back.

Thanks for keeping us posted on it.
I think we all spent to much time on that fuel pressure.
To late now but go back and read no 5 post. :grinyes:
Did you notice your security flashing at you? :lol:
Let us know how it goes.

No, my security light did not flash unless my door was open, which is normal I believe.

thx

No, my security light did not flash unless my door was open, which is normal I believe.

thx

10-4
The security should flash if it has a problem. But if it was shorted out that could have caused it not to tell you any thing. :grinyes:
When the security system trips normally it will start and run 30 seconds then shut down.
Did you get to try the carb cleaner test I suggested in post 16?
That one usually tells the story on the security system?
We hope the dealer gets it going good.
let us know how it goes.
MT

Does anybody know what size resister is needed for pass lock. Also this door deal can it be jumped or does it require a resister also?

Does anybody know what size resister is needed for pass lock. Also this door deal can it be jumped or does it require a resister also?

First would need to know which system CTD or TM.
But I do not think the resister by pass will work on ether one.
As far as I can tell door locks 3 wire switch that switches from a lock to a unlock signal to body computer.
I hope his dealer knows what he is doing on it.
Usually when a theft system trips in will start and run for 30 seconds.
And or run on carb cleaner.
And security light will flash.
Newer one or the CTD systems will flash head lights and blow horn and some of them will disable horn.
It was strange he did not have any of them symptoms.
But strange things happen or it could have been dead shorted.

I was wondering if you got your problem fixed??

I had my 2000 Chevrolet Silverado die on me here recently and we thought that it was the fuel pump, but it turned out to be just the coil. Thank God I didn't change the pump. Now it starts up with no problem.

Information for passlock.
http://www.catchacall.com/vatts.htm
http://www.motorage.com/motorage/data/articlestandard/motorage/292005/169809/article.pdf

Folks,

This is what my recipt said,

" Performed multiple diagnostics pulling apart many interior panels steering column covers and carpet and traced wires from pcm and bcm and determined that the rt rear pass lock module and pass lock sensors have failed causign wiring to overheat and cause connector pin concerns. R& R and replaced pass lock module and sensor. Repaired connector and reassembled vehicle. Recalibrated body control module and pcm and pass lock system"

The truck is now running. However, the dome light stays on all the time.

I dont know why, I thought maybe it was a pin switch, but I cannot even find any pin switches!

However, since this was not happening before I brought it to the dealer, i may bring it back and complain.

However, they may find something else that was shorted out and charge me another 1200 dollars to fix it....

And o by the way, they inspected the truck and found that I need all new brakes rotors and parking brake shoes, and I have some kind of seal leaking in the front axel. They wanted another 8 or 9 hundred to fix that stuff.

I declined. However, my parking brake does not work, and I think I will have to replace those shoes since it wont pass inspection.

Stand by for new post on how to do that.

Thanks once again for everyones help. Cheers.

Bob

Folks,

This is what my recipt said,

" Performed multiple diagnostics pulling apart many interior panels steering column covers and carpet and traced wires from pcm and bcm and determined that the rt rear pass lock module and pass lock sensors have failed causign wiring to overheat and cause connector pin concerns. R& R and replaced pass lock module and sensor. Repaired connector and reassembled vehicle. Recalibrated body control module and pcm and pass lock system"

The truck is now running. However, the dome light stays on all the time.

I dont know why, I thought maybe it was a pin switch, but I cannot even find any pin switches!

However, since this was not happening before I brought it to the dealer, i may bring it back and complain.

However, they may find something else that was shorted out and charge me another 1200 dollars to fix it....

And o by the way, they inspected the truck and found that I need all new brakes rotors and parking brake shoes, and I have some kind of seal leaking in the front axel. They wanted another 8 or 9 hundred to fix that stuff.

I declined. However, my parking brake does not work, and I think I will have to replace those shoes since it wont pass inspection.

Stand by for new post on how to do that.

Thanks once again for everyones help. Cheers.

Bob

Thanks for posting back how it went.
And we are glad they got the starting fixed.
It sounds like they had a tough time fixing it for some reason.:grinyes:
Makes you wonder how well trained them goodwrench techs are.:grinno:
What did they charge for it all?

I think the dome light switch is on the door latch.
On some I have got a the working by spraying skunk oil on the door latch.
:grinyes: :grinno: :lol:
Good Luck
MT

I'm glad they got it fixed but it sure took long enough. I imagine you needed a rental vehicle also or did the dealer supply one.

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