Blazer 96 starts and dies then does start

I have searched the forum to find a similar problem but with no luck.

The problem:

I tried to start my blazer it first kicked on then right away it turned right off (like it wasn't getting gas). Tried to start it again but nothing, it turned but didn't turn over after a few times the turn became very weak. I will be testing the fuel pump tomorrow but was also wanting to know how likely it could be that the problem is a bad sensor. Also after a few hours or a day the SUV does the same thing starts, then dies, turns then the turn becomes very weak without starting the car. For that reason I started to think maybe it was a sensor. I have not been able to drive my car since the problem started which has been a couple of days. I have pretty much ruled out electrical problems ( alternator. starter, battery). Any information would be great, thanks.....

I have searched the forum to find a similar problem but with no luck.

The problem:

I tried to start my blazer it first kicked on then right away it turned right off (like it wasn't getting gas). Tried to start it again but nothing, it turned but didn't turn over after a few times the turn became very weak. I will be testing the fuel pump tomorrow but was also wanting to know how likely it could be that the problem is a bad sensor. Also after a few hours or a day the SUV does the same thing starts, then dies, turns then the turn becomes very weak without starting the car. For that reason I started to think maybe it was a sensor. I have not been able to drive my car since the problem started which has been a couple of days. I have pretty much ruled out electrical problems ( alternator. starter, battery). Any information would be great, thanks.....

check the fuel filter...

The trouble sounds like your fuel pump went bad. Couple of things to check first. Check your battery to make sure you got a full charge. Sounds like its weak. Next, Check your fuel pressure at the check valve to ensure that you have around 60 to 65 psi. If its below 60 psi. You can try and change your fuel filter if it hasn't been changed and see if that will help. If not. Your fuel pump probably bad.

Hi. Is the engine surging at all when it starts? If it is I got a great tip here to replace the spark knock sensor and it worked. This wouldn't account for the slow turning after it starts but might solve the starting problem.

Well i did what Gabe said i checked the battery and the charge was low, had it replaced. Got it in and it took a couple of tries but the blazer started let it run for a little while and took it out for a spin then when i was getting back it died again and wouldn't restart. So now I am leaning to thew alternator. Don't think it would have started if it was the fuel pump, so doubt that is it but I am going to check out the alternator and the starter tommorow. Also when I was driving the car didn't seem to have much power and was hesitant when I tried to accelerate.

Any Ideas????
Could it still be the spark knock sensor?

Before you run out and by a alternator. Check the voltage output first. Jump start your motor first making sure that you nothing on (lights, AC Fan,ect.). Your alternator should be putting out around 14 volts.

Bad fuel pump or clogged fuel filter!!!!

My dads mid 90s Chevy truck did the same thing described here . Long story short , are you using a factory ignition key or a duplicate copy. Some models have the PASSKEY microchip buried in the plastic . Dads would crack and run about five seconds and die . He had it toed to a dealership where they pulled the code and it was a security code . try a different key . Rob

P.S. The security disables the fuel pump.

Ok tried to check the alternator with the car not on it tested 12.15V tried to start the car but couldn't tested it right after that and it was 13.35V. Everything was off. I also noticed that the large hose connecting the air flow from the filter to the engine was unhooked. Reconnected it but was no help. When I did get my car started it idled fine then I tried to give it some gas while in park and it died.

Still lokking for some ideas anything helps.
and thank you for all you help.

OK you need to check your fuel pressure. Like I said before. I really sounds like you got a pulled fuel filter or a bad fuel pump. Change your filter first. Check fuel pressure again. Still not up to spec's. Change your fuel pump.

Like Gabe25 says.
You have got to have full fuel pressure.
Do not leave home without it.
Get a fuel pressure gauge on it and check cold start pressure and engine running pressure and tape gauge to mirrow or windshield and check it running on the road.
The shut it off and check for fast leak down.
Them injectors will not squirt fuel cold unless the fuel pressure is up to full specs.
Post back fuel pressure readings.
MT-2500

Well I did the old fashion pressure test. I removed the fuel filter and tried to start the car but nothing absolutely no pressure. So I will now take my car in to replace the fuel pump cause I dont think I can do it myself. What I dont understand is why my car would continue to start if the fuel pump was not suppling any gas.

Well thanks for all your help....... :-(

Good Grief easy does it.
Do not just go in and tell them to replace the fuel pump.
Tell them to check it out and find out why it will not start.
It may have many different problems.
Check it out before throwing parts at it.
MT-2500

Well I did the old fashion pressure test. I removed the fuel filter and tried to start the car but nothing absolutely no pressure. So I will now take my car in to replace the fuel pump cause I dont think I can do it myself. What I dont understand is why my car would continue to start if the fuel pump was not suppling any gas.

Well thanks for all your help....... :-(

As MT-2500 says, Don't run off and just replace parts not knowing if that is the problem. You still need to find out if infact your getting voltage to your pump.

As MT-2500 says, Don't run off and just replace parts not knowing if that is the problem. You still need to find out if infact your getting voltage to your pump.

Thanks for the advice I will do just that. I am having it checked out later this coming week.

Ok I am trying to test the fuel pump relay to see if the pump is getting the signal to turn on. I was told there is a wire that goes to the pump itself and was also told to check the wire for any electrical readings (with a voltage meter). But i dont know which wire it is if anyone knows please fill me in. I am trying to find it in the manual but it seems to be a little vague in this area. Also in another thread 1 person said the relay was the in the glove box and was the the 2nd one from the drivers side but another said it was the first on can some one clarify which one it is.

sounds like the fuel filter is clogged.

Nope, least I dont think so, changed the fuel filter 3-4 months ago and changed it again just to be safe couple days ago.

Nope, least I dont think so, changed the fuel filter 3-4 months ago and changed it again just to be safe couple days ago.

Excellent, well, when it dies, turn the key off for 10 seconds and then just turn it to on just before start and see if you can hear the pump prime.

Got it started ran for about 3-5 secs then died. waited the ten seconds and turn the key to on position but couldn't hear the pump priming. Also when i pulled off the filter I tried to start the car to see if there was any pressure or any flow what so ever but there was no flow at all. I would figure at least some flow/pressure would be present which has lead me to believe it could have something to to do with the fuel pump relay or the wire connecting to the fuel pump not recieving a charge signal to turn on or prime.

You are getting closer, some great diagnosis you are doing there.

Check the relay, then the wiring, then the grounds and then the fuel pump itself.

Checked the relay actually went out and bought a new one too, but no luck. I am a little confused about the wiring though I know that it is a red one but I am not sure if I have the right one and am unsure a what point to test it and exactly how. Also I bought the book but the skecth of the wiring is vague and shows no realtion to the blazer. I do have the voltage meter and know how to use it but I am unsure with this one (I just don't want to get it wrong).

Here is the wiring in a pdf if it is A 4.3 W ENGINE.
The red wire is fuel pump primer wire.
Hook a fused 12 volt jumper wire to it and your fuel pump should run.
Gray feeds fuel pump. And do not forget the fuse check.
http://members.troublecodes.net/crunch/96bfuel.pdf
MT-2500

Starts ok, but will not stay running. You might want to change out the fuel pump oil pressure switch (Top rear of engine near distributor), if your oil pressure is OK and fuel pump pressure OK (60 - 65 psi).

In the start mode, the fuel pump relay is closed, powering the fuel pump. After the engine starts, the oil pressure switch is closed keeping the fuel pump running. If the engine stops, no oil pressure, fuel pump stops (Safety / Fire). This Can be do to too low oil pressure at sensor, bad pressure switch (Internal weak in the sensor slowly allows the the switch to open) or it could be electronic control circuit stopping the engine because of other problems (need a scan tool to check processor / other sensors).

Digitdav ^^
The fuel pump relay powers the fuel pump on eng start or engine run and key on fuel prime.
The only thing the oil pressure switch does is power the fuel pump in case the fuel pump relay quits.
It is just a saftey device to keep the engine running when relay fails.
Late model systems do not even us it.
MT

Digitdav ^^
The fuel pump relay powers the fuel pump on eng start or engine run and key on fuel prime.
The only thing the oil pressure switch does is power the fuel pump in case the fuel pump relay quits.
It is just a saftey device to keep the engine running when relay fails.
Late model systems do not even us it.
MT

Not having all the circuits drawings and from what you say the fuel relay would stay energize, if the engine stops and the Ing switch is in the run mode. If that is true when the fuel pump would be running until I turn the Ing switch to off.

Is the Fuel pump prime (b2) a ON with a time delay OFF at start and is c2 connect to the start, run or processor circuit?

On a car that the engine is running ok, a way to check is to disconnect the oil pressure switch, if it stays running then I am wrong, if it stops then I am right.

keep it simple.
Take a 12v fused jumper wire and feed it to the fuel pump prime connector w/relay installed if the pump runs that rules the pump out if the pump doesn't run post back for further instruction.
chris

Digitdav ^^^
The oil sender unit does not power the fuel pump.
It is only a saftey switch to power the fuel pump in case the feel pump relay quits.
Engine off key on does not power the fuel pump or relay.
When you first turn key on engine off the the PCM gives the fuel pump relay a 30 second prime.
Then when you start cranking the engine the pcm powers the fuel pump relay based on crankshaft signal.
Then when engine starts and has crankshaft signal the pcm keeps power on fuel pump relay.
When you turn key off the pcm does not power fuel relay.
Also when you turn key off the oil pressure switch has no power to run fuel pump.
The oil pressure switch is a old wives tale. But a lot of mechanics still beleive it for some unknown reason.
The only cars that the oil pressure switch powered the fuel pump was a couple of year models around 1985
MT

Actually the pcm only runs the fuel pump for 2 sec KOEO then 2 sec again when the key is turned off. and it does run when recieving a rpm signol from crank sensor.


The 1996 does have an oil pressure switch that once the vehicle is running and under extended crank WILL RUN THE FUEL PUMP. so the problem is most likely after the ops in the power or ground supply if an electrical problem

the newer vehicles have done away with the ops such as my 2000 does not have it. but the 96 has it i looked at a wiring diagram on alldata.
chris

The oil pressure switch is just along for the ride.
It does as much good as the tits on a boar hog.
All it does is put 12 volts to the fuel pump that already has 12 volts on it.
It is only a saftey backup to power the fuel pump if the fuel pump relay quits. And only powers it then when the oil pressure is up.
MT :smile:

Thats Not The Point! It Proves Where The Problem May Be If The Engine Already Runs It Should Continue To Run If The Switch Works Pointing To That Part Of The Circuit Maybe Corrosion At The Connector To Be An Intermintant. Or Corrosion In The Wire Causing A Voltage Drop Affecting Pump Rpm After The Circuit Heats Up!

This honestly sounds electrical.

Like something dead shorting out with heat.

I think the fuel pump is the problem here.

Well after all the speculations I got in there and it turns out the the fuel pump was priming but it was so faint that it wouldnt pump any fuel. So I replaced and now all is fine been running great for 2 days now. Thanks for all your help and replies it gave me some great insight. Will check back for any other problems in the future hpefully there wont be too many!!!!

Well after all the speculations I got in there and it turns out the the fuel pump was priming but it was so faint that it wouldnt pump any fuel. So I replaced and now all is fine been running great for 2 days now. Thanks for all your help and replies it gave me some great insight. Will check back for any other problems in the future hpefully there wont be too many!!!!

sweeet!