92 C1500 Starting And Stalling Poblems

trans1973 · May 2, 2009

Hey guys, first of all thanks for all of the great posts I've read on here. It's helped me get as far on my truck as I have, but im still having problems.

My truck is a 92 C1500 with a 4.3l.

About 5 days ago I got caught in a nasty rain storm and my truck stalled out at a stop light. After about 15 minutes of checking fuses, banging on fuel tank and relay, and wiggling wires it fired right up and ran without a problem. I checked everything I could think of when I got home and could find no bad wires, pulled cap and it was fine, nothing apparent wrong. 2 days later I was driving to work on a dry day and it died again, same thing, waited 15 minutes and it fired up and drove fine rest of the day. Then on the way home it died but would not restart so I had a buddy tow it. Next morning it fired right up but I didnt dare drive it. Got home from work and tried it agian and it wouldn't start. Kept checking things out and was finally able to get truck to start by disconnecting battery for 10 minutes then reconnecting and it would fire right up. But as soon as it would run for 15 minutes or so it would die as soon as I put it in gear and than it would not restart again. The battery trick quit working so I turned to ether. It would fire up on ether but would die within seconds, so had spark but no fuel. Got frustrated and let it sit for a while. Than a range of parts and tests followed, so heres where I'm at:

New cap, rotor, plugs, and wires.

New fuel filter

New thermostat (just because it needed one)

New temp sensors (both)

Cleaned, checked, and added grounds (including the 2 at the front of the intake by thermostat)

Tested fuel pump, relay, and oil pressure switch

Checked for vacuum leaks, only thing I found was cracked elbow where pcv hose hooks to TBI

So after all of this, this is what I have. Truck will not start on its own unless it sits for hours and that only works sometimes. It will fire up on ether and stay running now instead of stalling once the ether runs out. Still stalls out when it is put into gear. Seems to be running really rich. Can notice change in pitch of engine noise when you press on brake and when you move gear shifter (its an automatic). Also seems to have an oil burning smell thats new to me. I'm lost. When it runs it runs great and I had zero problems with this truck until that rain storm.

Sorry for so much info, just trying to be thorough. I'm lost on this one. Any ideas? And thanks in advance guys

superjim · May 2, 2009

The change in engine pitch when you press on the brake...that may mean a vacuum leak as the brakes are run from vacuum.

One other thing to check if the fuel pressure regulator and crankshaft sensors.

Also, unplug and dry out any connections you can get to.

May be just a drop or two of water in one of them.

trans1973 · May 2, 2009

Where is the regulator on these? And did they have a crank sensor in 92? Will double check and make sure connections are dry in morning. Thanks for the advice

superjim · May 2, 2009

Where is the regulator on these? And did they have a crank sensor in 92? Will double check and make sure connections are dry in morning. Thanks for the advice

I think the regulator is behind the throttle body..towards the firewall.

Not totally sure if 92 has the crank sensors...but wanted to mention it...just in case.

bill190 · May 2, 2009

If the above does not work, I would suggest getting a factory "Fuel and Emissions Service Manual" (Get from dealer). These things are so complex these days, there are all sorts of things to check and test. These manuals have step by step troubleshooting instructions.

Here is a hint of some of the stuff you would need to check for just the fuel system...

http://www.asashop.org/autoinc/june98/techtotech.htm