Will not stay running

Tiny
BINDERY SKIN
  • MEMBER
  • 1991 CHEVROLET S-10
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 174,000 MILES
4x4 starts but shuts off as soon as you let off the gas.
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Monday, January 17th, 2011 AT 4:31 AM

60 Replies

Tiny
RASMATAZ
  • MEMBER
This sounds like you have a vacuum leak or the IAC valve is gummed up or not working here are two guides to help you see whats going on and fix the problem.

https://www.2carpros.com/articles/stall-at-idle

Please run down this guide and report back

Cheers

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Monday, January 17th, 2011 AT 10:53 AM
Tiny
MAHENDRA DAHYA
  • MEMBER
I had this problem it was the throttle body gasket that was blown. FYI
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Tuesday, August 21st, 2018 AT 3:25 PM
Tiny
CANTER6
  • MEMBER
  • 1991 CHEVROLET S-10
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 197,000 MILES
I just bought a 91 s10 4.3l tbi, last week that had been sitting for a few months. Yesterday coming back from my lunch break I was pulling into the parking lot when the engine died. On re-start, it would turn over and run for a second, then quit. Now if I feather the throttle it will stay running (really bad and even backfire through the "carb", almost like it is out of time) the faster I feather it the smoother it will run, which leads me away from timing issue and into fueling, when I turn the key I can hear the fuel system pressurizing, and I just got back from an 1100 mile trip this weekend with no problems, so condensation in the tank isnt looking to be an issue, I check the dist. Cap and it isnt loose. I have not tested the fuel pressure as of yet, which I plan on doing hopefully today if the storms clear up. Ive read up a bit before posting this, that possible reasons could be the egr valve being stuck open, and/or the ecm being toast. Problem is I haven been able to locate the ecm to visibly inspect the card, (only had the truck now for about 3 days. And two of them have been on the road driving it.

EDIT******************************
last night fed her starting fluid through the throttle bodie, and she started up and ran good (as long as starting fluid keeps being squirted), BUT the injectors ARE pulsing and you can visibly see them squirting. Now im at a loss, going to pull off the injector assembly today/tonght. And see if garbage has collected in the bottom of them. Oh yeah the cap/rotor/ and ign. Ctl mod are new as well.

UPDATE*********************************
jumped a and b under the dash and the only code that came up was 24 IIRC which according to the guide I found online is a VSS code. Doesnt seem like it would be a reason for the no-start, but figured I would hrow that in as well.
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Tuesday, August 21st, 2018 AT 3:26 PM (Merged)
Tiny
RACEFAN966
  • EXPERT
First let me say don't use starting fluid it is not good on a engine at all if you must do something like that use carb cleaner it is less harmful. Now with that said when was the last time you changed the fuel filter? Have you done a fuel pressure test? Get back to me and we will go from there.
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Tuesday, August 21st, 2018 AT 3:26 PM (Merged)
Tiny
CANTER6
  • MEMBER
I havent changed anything on it other than cap/ rotor button, and ignition module, since I purchased the truck. I went out last night to look for a port to check fuel pressure. And was unable to locate it (traced fuel line from body of tbi all the way down to where I could not see it anymore below the engine.
I plan on replacing the fuel filter this weekend (saturday) as I am unableto get out there unitll after work, and have daylight constraints, in the parking lot it is in.

Where would the check port be located at?
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Tuesday, August 21st, 2018 AT 3:26 PM (Merged)
Tiny
RACEFAN966
  • EXPERT
I would first change the fuel filter so you can rule that out. As for a port to check pressure there isn't on on this model. They sell a 40 dollar adapter that you put in place of the fuel filter just for testing. It should be about 15 psi. Let me know how it goes.
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Tuesday, August 21st, 2018 AT 3:26 PM (Merged)
Tiny
CANTER6
  • MEMBER
Just changed the fuel filter out in the parking lot (lunch break) the filter that came off, was reletively new looking, and had VERY little debris in it on the input side and next to none on the output side, tried turning the truck over and still nothing, I will see if I can locate a pressure tester from one of the guys in the shop out back and get back to you,
one quick question, when turning the key to the run position (not start) you can hear the fuel pump relay engage and the pump whine to pressurize the system, then a click again, is this normal?
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Tuesday, August 21st, 2018 AT 3:26 PM (Merged)
Tiny
CANTER6
  • MEMBER
Okay got a pressure tester, from one of the guys out back, gonna see if I can get one of those adapters you told me about,

i have the upper part of the tbi removed at this time to go ahead and rebuild it it with new gaskets etc.
And when I pulled it off it was pretty filthy, I disassembled it and cleaned it in the parts washer.
While it was off I turned the key to the run position (fuel lines disconnected from the tbi housing) and got alittle gurgle and a brief spurt of fuel,

its looking more like the fuel pump now, as I was easily able to hold my thumb over the line, and not spray fuel. Going to check pressure anyways just to be sure.
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Tuesday, August 21st, 2018 AT 3:26 PM (Merged)
Tiny
JCROUCH18
  • MEMBER
  • 1991 CHEVROLET S-10
  • 4.3L
  • V6
  • RWD
  • AUTOMATIC
  • 200,000 MILES
The problem is getting worse every week. When i'm going down the road the truck acts as if it is running out of gas and starts sputtering. When i'm at a redlight/ stop sign the truck stalls out as if it were running out of gas, so I accelerate and after its done sputtering it goes back to normal. I just changed the fuel filter on it and that didnt make it run any better. Also started putting mid-grade in it and it seemed to be better the first few days and now it is acting like it was before. It also drinks a lot of gas if that helps diagnose the problem in anyway. PLEASE HELP!
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Tuesday, August 21st, 2018 AT 3:26 PM (Merged)
Tiny
RACEFAN966
  • EXPERT
Yea sounds like the fuel pump is going to need to be replaced. You will have to drop the tank to do this too. Let me know if you need anything.
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Tuesday, August 21st, 2018 AT 3:26 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
Several things could be causing this. First, have you checked the computer to see if there are trouble codes stored? Have you checked fuel pump pressure to make sure it is within the manufacturer's specs and the pump is producing proper pressure and the regulator is working properly? When was the last tune up?

Let me know the answers to the above questions. Also, just FYI, if this is a 4.3L, they had problems with the spider under the intake (the injection system). The regulator would go bad and cause similar issues. Let me know the above answers first, then we can go from that point. NOTE: I will need you to check the function of the fuel pump and fuel pressure regulator.
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Tuesday, August 21st, 2018 AT 3:26 PM (Merged)
Tiny
CANTER6
  • MEMBER
Dropped the tank today (if I ever have to replace the pump again im cutting a hole in the bed ha ha ha) seriously though the truck really is in bad shape (was in a crash and now has body panels from 88-91 on it, taste the rainbow! Lol

anyhow, turns out the pump was good it was the hose between the pump and the rest of the fuel pump assembly had split, changed the pump along with it, and sock, and keeping the old pump in case I ever need it to siphon somthing or what not.
Thanks for slowing me down, and focusing my efforts more carefully!
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Tuesday, August 21st, 2018 AT 3:26 PM (Merged)
Tiny
JCROUCH18
  • MEMBER
There are no codes in the computer. And I don't know how to check the fuel pressure. I did a tune-up on it around February, (air filter, oil, oil filter, spark plugs, spark plug wires.) And this is a 4.3.
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Tuesday, August 21st, 2018 AT 3:26 PM (Merged)
Tiny
CANTER6
  • MEMBER
Tried leaving you some positive feedback as well, but it seems I have none to give :/ just know I appreciate you!
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Tuesday, August 21st, 2018 AT 3:26 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
I need to know one more thing. Is this a multi port fuel injected engine or does it have TBI? Also, can you locate the fuel pressure regulator?
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Tuesday, August 21st, 2018 AT 3:26 PM (Merged)
Tiny
RACEFAN966
  • EXPERT
Hey no problem thats why I do this. I also volunteer my time to the needy for there car problems too. I guess it is just my calling and I like working on cars too. Thanks for you comment and if there is anything else you need just ask. You have a great day and God Bless.
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Tuesday, August 21st, 2018 AT 3:26 PM (Merged)
Tiny
JCROUCH18
  • MEMBER
It is TBI, and no I don't know what to look for honestly.
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Tuesday, August 21st, 2018 AT 3:26 PM (Merged)
Tiny
DEBRAGERIK
  • MEMBER
  • 1991 CHEVROLET S-10
  • 4.3L
  • V6
  • 2WD
  • AUTOMATIC
  • 140,000 MILES
Well yesterday the truck just quit, stayed going for a minute feathering the pedal. Today changed the IAC Valve, fuel filter and one of the vacuum hoses. The truck will start but not stay running. It starts strong but as soon as I release the pressure on the gas pedal it stalls out. I also need to know how to find and repair a leak in the ac lines or wherever it is because I added refrigerant and it all leaked out. Sorry I didn't have money to donate at this time but I am on disability and trying to go back to school. Thanks for your time.
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Tuesday, August 21st, 2018 AT 3:26 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
Here is a generic video showing how to check fuel pressure on all vehicles. I say generic because it isn't for one specific type of car but rather a general overview of how it's done. It is actually very informative. Watch it and let me know if you feel it is something you can do.

I have a feeling the fuel pressure regulator is going bad and allowing too much pressure to get to the injector. However, the opposite could be true too. There could be too little pressure due to a weak pump.
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Tuesday, August 21st, 2018 AT 3:26 PM (Merged)
Tiny
HMAC300
  • EXPERT
Th a/c system has to be checked with an electronic tester and it has to be run along lines, seals, etc. Check your fuel pressure with a gauge autoparts rent it. Shold be 41-47 psi
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Tuesday, August 21st, 2018 AT 3:26 PM (Merged)

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