Mechanics

WHY IS MY TRUCK STALLING WHEN IT WILL RUN PERFECTLY FOR 20 MINUTES?

1991 Chevrolet Silverado • 149,000 miles

My truck developed a miss. I did a complete tuneup, new coil, new EGR, rebuilt TB with injectors. This truck will run like a watch for the first 10-15 miles. Then it will start a slight stumble when I accelerate and it will gradually get worse until it shut's off completely. It will restart everytime but with the same issue. If I wait 5 minutes it will go for a few miles but then shut off again. I found no codes jumping out the diagnostic port. I even gave it a code by removing the TPS wire just to see if it would give a code and it did. I also have found unplugging the air sensor on the TB does nothing. No code, no engine trouble
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Redc338
March 14, 2012.



Start by checking the fuel pressure.

Cadieman
Mar 14, 2012.
I'll have to buy a gauge and a filter jumper. And It will do this in park Idling, after the 20 minutes of driving, so I can check it safely, not hanging out my door on the highway!

Tiny
Redc338
Mar 14, 2012.
Is it normal for a pump to lose pressure gradually like that? Then start right back up?

Tiny
Redc338
Mar 14, 2012.
I also noticed the relay seems hot

Tiny
Redc338
Mar 14, 2012.
Rent the gauge from the parts store. Get the gauge hook it up lay the gauge on the wiper arm so you can see the gauge dial. Then close the hood leave the hood on the safety latch. Drive the truck and when it quits read the gauge. Then come back. Gm pumps overheat and stop and than will run ok again till they stop again. Also the hose from the pump to the sending unit gets porce and it sucks air.

Cadieman
Mar 14, 2012.
On a 91' there is no test port/Shrader valve. I'll have to remove the filter and "T" off with a hose

Tiny
Redc338
Mar 15, 2012.
When it quits spray the intake with starting fluid. Does it restart?

Cadieman
Mar 16, 2012.
I actually thought of doing that as it is cutting off. It will restart on it's own everytime, first crank

Tiny
Redc338
Mar 16, 2012.
I'm replacing the pump and relay this weekend. If this doesnt fix it, my next purchase will be dynamite!

Tiny
Redc338
Mar 16, 2012.
Gm pumps get hot and stop and go like that. Good luck let us know what happens.

Cadieman
Mar 16, 2012.