'93 Jimmy Vortec 4.3 stalls at idle under load

wb8yjf · #1 10-12-2006, 07:46 PM

I'm posting this for a '93 I have been borrowing that is driving me & my buddy (owner) NUTS! It developed stalling problems but only while in gear & idiling (ie: stop light, etc). When I first borrowed it it was running fine (he has had this problem off & on for about 2 years). Then suddenly it is stalling. Sometimes it fires back up, TODAY it died while I was at the drive thru window at a McDonalds! I couldn't get it started at all. I pushed it out of the way (of some growingly impatient people behind me) and ran the battery down trying to get it started. Called my buddy who was just about to leave work, he showed up, jumped the battery & it fired right up! Made it home - foot on gas & brake when coming to a stop - so I could keep it revved a bit so it wouldn't stall.

I'm thinking IAC module...He replaced the EGR previously. We took the IAC out and "eyeballed" it & it looked fine. Wadda you guys think? Anyway to test this thing with a meter? He replaced the pump awhile ago & fuel pressure is holding. It dosn't stall when in neutral.

Man, me & Jimmys have had a rough time....

jdmccright · #2 10-18-2006, 06:17 PM

Welp, my thought is that you have low fuel pressure while at idle. This can be from a failing battery and/or alternator, a failing fuel pump, or even simply corroded terminals. If the fuel pump isn't able to keep up for one reason or the other, then the engine will die from fuel starvation. Another thing to look at is the fuel pressure regulator. This can cause hard starting and, in severe cases, stalling. This should be a good start...good luck!

wb8yjf · #3 10-18-2006, 08:14 PM

Quote:

Originally Posted by jdmccright

Welp, my thought is that you have low fuel pressure while at idle. This can be from a failing battery and/or alternator, a failing fuel pump, or even simply corroded terminals. If the fuel pump isn't able to keep up for one reason or the other, then the engine will die from fuel starvation. Another thing to look at is the fuel pressure regulator. This can cause hard starting and, in severe cases, stalling. This should be a good start...good luck!

Thanks for the reply! I know he replaced the battery/alternator & I looked at the battery connections - clean and tight. Fuel pump has less than 5K miles on it & pressure builds OK and stays. One thing I know he DIDN'T replace was the regulator. I'll pass this on...I have a new regulator, so I'll give it to him to try. What about the IAC module, though? When I was driving it, I could easily go 40 MPH w/o a foot on the gas. Idled mighty high (no tach - so not sure of the RPM's). It would toss a code, but wouldn't you know it - it cleared when the car was shut off or was idling...

Possum667 · #4 10-21-2006, 07:36 PM

dono if this has anything to do with but. i know most of the people i know and even i had a problem of stalling or server stuttering at idle. everyone i know just replaced the idle air and the throttle position. they usually arent to expensive so you may wana thinl about the throttle position also.

wb8yjf · #5 10-27-2006, 05:26 PM

He hasn't had the time to fool with it yet. When he does, I'll post results. Thanks for the input!

riptide44 · #6 10-28-2006, 02:16 PM

i would check the iac valve for sure it could be faulty or the air passage behind it clogged - a clog would reduce air and make the iac go full out to try and compensate , tps is another good possibility ( i have personally had one that failed and caused stalling when coming to a stop sighn) as well as the ignition module in the dizzy ( does stall after it gets hot and then starts when it cools down ) thats a classic ignition module problem .so those are the cheap and easy ones .. next would be - do you smell fuel out the exhaust ? that would lead to a bad cpi unit (or regulator if your lucky .)

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