2002 s10 4.3lV6 won't start

Replaced battery, did not help. It seems to crank fine and I can definitely hear the pump kick in for a couple seconds at first, but just will not start. It sat for several days in cold weather. Based on what I have read here I am thinking it is the fuel pressure, and that I need to get the tool to check that. There is about 1/4 tank fuel now, it seems that once before when it sat for several days around 1/4 tank it started and ran rough, then ran fine after I filled the tank. Could it be as simple as filling the tank? Any ideas/insights greatly appreciated.

Add 5 gallon to be sure you are not low on fuel.
And check fuel filter.
Buy /borrow /rent a fuel pressure gauge.
Some parts places loan tools.

The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold and fuel pressure testing guide line.
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.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding 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 in system.
Post back fuel pressure readings.

Thank you for the response! I am going to try pouring some more fuel in first then. If that does not work,a question about checking the fuel pressure. I am wondering if an OBDII scanner can do this, or if a scanner can at least tell me if there is a fuel pressure problem? If not, I wanted to make sure it is do-able to check the pressure when the car is not starting, and if so the best method for doing that? Thanks again.....

Hook up a fuel pressure gayge and check pressure.
Watch key on prime up pressure and cranking fuel pressure.
Check direct fuel pump pressure.
Post back what pressure readings you can get.

A scanner will not read fuel pressure but will show high fuel trims if fuel pressure is running low.

Thanks again - I am going to get the gauge today and check it. Assuming the pressure reads low, is this something complicated to repair?

Go threw the test as outlined to see where the problem is.
Post back how the test goes.

Okay I bought a pressure tester, and am now searching for the schrader valve. Could you tell me where it is on this model? Thanks

Okay I looked some more and found the Shrader valve. :smile: I hope I did this right, I got the following numbers:

1. With ignition on so that fuel pump was humming only, it went to 63.

2. When fuel pump stopped humming after a couple seconds, it fell to 53.

3. When trying to start/crank it, the needle got jumpy but seemed to hover right around 63.

4. With the key completely off again, it held at about 51, until I hit the relief valve on the tester and it fell back to zero (or very close to zero).

Thanks again for your help!

Jumpy needle is not good.
You need 64-65 lbs steady pressure for a cold start.
You need to check full fuel pump pressure.
Full pressure should be around 95 lbs full pressure.

The fast leak down to 53 is not good.
Prime it with a little carb cleaner spray or gas and see if it will fire.

I'm not sure how to do these things. Are you saying to get it started somehow by priming something, then check pressure at full throttle? i am wondering still if I should get a scanner, would that help narrow this type of problem to a something specific? Thanks, Kyle

To prime it.
Spay carb cleaner into TBI where the buterfly is while cranking.
Go back and read the fuel pressure test.
Full direct fuel pressure with return line blocked off is full pressure.

Okay I think I found the butterfly, I was able to rotate it partially like clock hands using my finger. So, I will get some cleaner for that. I below that part a small puddle (maybe the accumulation of about a teaspoon) of what appears to be fuel. I'm going to clean it out and see if it accumulates again when I try starting next time. On the return line, I really have no idea which one that that is. Any help or diagram there would be much appreciated. Thanks.

Can't get it to start even with priming.

Can't get it to start even with priming.


Are you sure you are getting good hot blue spark to all plugs?
Pull plugs and see if they are wet on the end with gas.

If plugs are wet or fouled out drop new set of ac plugs in it.

Awe heck no I have not checked the plugs, not even sure where they are :confused: I'll try to figure that out...

You will find them on one end of the plug wires.
Also check for good hot blue snappy spark to more than one spark plug.
Good Luck and let us know how it goes.

Hello I have a 2002 as well with 157000 now. I have had this same issue 4 times. Three times fuel pump (learned the hard way to stick with ACDelco) and once it was the distributor cap and rotor that needed replacent. I know many things will cause this issue and you are on
track by checking your fuel pressure at the rail. Should it turn out to be either do not try and save a buck useing aftermarket fuel pumps or distributors.
You can find a brand new ACDelco fuel pump as low as 140 dollars on ebay. Only the OEM pumps will deliver the fuel at 60 to 65 psi for any length of time. The two after market pumps I tried where the PrimeSource which lasted for a whole 300 miles and they wanted a certified letter from a mechanic saying it was bad before they would honer the lifetime warrenty I paid extra for...Horrible company. Stay away. The other was an Airtex which lasted about 4 months. The OEM replacement is at 62000 on it. I even get a little better fuel economy when useing the OEM 23 mpg at 70 mph. Good luck and keep us posted on the fix.

The center plug on the drivers side is bear. Chilton recomends breaking loose motor mounts lol....spark plug socket with a rachetting wrench to fit it works great without having to lift the motor.