89 s-10 Blazer 4.3 , 164000 miles. Engine runs for about 5 min. and then shuts off. If you turn ignition off and then on you can hear fuel pump come up, turn to start position and engine turns over but no fuel sprays from injectors.If you wait for about 30 min engine will crank and whole process starts again. No codes
Replaced: Fuel pump, screen, filter , fuel pump relay , oil pressure sending unit , electrical tune up , rebuild TBI and regulator, Idle air control valve.Can't find any vacuum leaks.Engine used to idle and run rough but idles pretty good now , still alittle rough but ok.Seems like something is shutting off injectors as some component heats up .
Engine just heats up when problem happens.
This is driving me crazy!

 

..."Seems like something is shutting off injectors as some component heats up ."...

BINGO... I had an 88 a few years ago and let me tell you... The problem you describe happened to me right on Route 115, 200 feet from the entrance to the Pocono 500. Yeah, on the Friday night before the race.

ANYWAY... What you need to do to test my theory is to go to your local auto parts store and see if you can rent, buy or borrow a noid light. This light tests for the presence of injector pulse. It is wired across the injector harness. I would test for the pulse in the morning when its cold, then test it again after you let it idle till it shuts down. If the injector pulse stops, your issue is most likely inside the engine computer, which is located behind the glove box. Sometimes the old computers will lose some solder joints, or get damp if the windshield ever leaked. I had 4 different issues in 2 different trucks that had that computer in that location.

Before replacing it, inspect the plugs, harnesses, and connections at the computer. Could be a loose wire...

You can also try tapping on the computer LIGHTLY with a plastic screwdriver handle and then try starting it... that should prove loose solder connections.

Anyway, if you take my advice and conclude that the computer is the culprit, email me directly and I'll send you a link to a cheap place to find a good replacement w/a warranty.

Good Luck
~Mark

 

Check the ignition module in the dizzy. Pretty common problem on s-series and they control the fuel pulse. Yours sounds like a classic description of a bad one.

 

Turns out it was the coil located inside the dist. Runs great now. Didn't realize that computer won't let the injectors fire if there's no spark.When it would stop I would check for fuel in the TBI and that threw me off.
Thanks for the info !