I just bought an 89 S10 pickup 4.3 liter 4x2 with 114,000 miles. The truck sat for 6-9 months, only being run in the driveway for a few minutes at a time. The truck starts right up after it has sat overnight to cool down. After it has run for as little as 5 minutes and shut off it will not restart (just cranks). It acts like it has no spark/ignition. It does spray fuel into the intake and i can smell fuel when i crank it. I drove it about 40 miles today with no problems until i turned it off, and it didn’t restart, it has been 3 hours and still won’t start. IT did the same thing yesterday after driving about a mile, ran fine until i shut it off and tried to restart. it sat overnight and fired right up in the morning. I haven’t tried to do anything yet, I want to see if anyone else is having these problems, or can help. Thanks very much in advance.
“It does spray fuel into the intake and i can smell fuel when i crank it.”
Right, but maybe you have too much fuel. Given no reference to a carb I’ll assume fuel injected. If so, then you might have either a leaky pressure regulator or leaky injector(s) that are actually flooding the intake on warm restart. Try starting it as if flooded - floor it and turn the key, let up slowly if/as it fires. If that works, pull the vacuum hose from the pressure regulator - if you find any liquid fuel in the vac hose, replace the regulator.
Another likely cause is breakdown of ignition components b/c of heat - get a spare plug or a spark tester that you can hook up when this happens. See if you have spark.