cranking fine, but occasionally doesn't start??

[angry inch]

My '91 s-10 with 4.3L sometimes won't start, but seems to have lots of cranking power. It will start, however, if I roll(jump)strart it... Once it has run, it will start fine again until it hasn't been run for a few hrs. any Ideas??

[jsgold]

To know what's really going on you need to d/c fuel pressure, and verify spark. A lot of possibilties. Mine just had the coil and distributor assy replaced due to stalling, and hard starts. Sometimes would start OK, then would not start until cooled down. Fuel pump could be failing, filter clogged, or injector assy could be failing. best to start with a fuel pressure test. Should be 55-60 lbs+. If not check filter. If Ok then check fire. Mine would fire then stop suddenly. The ignition module at the base of the distributor was bad. Check for trouble codes stored in computer. clean and check EGR valve, AIC, and if these all check out, most likely suspect injection assy. Only way to check that is to remove the plenum. Others here can guide you through that. hope this helps!

[jackass#1]

take it to autozone or pepboys and have battery and alt checked. its a free service. if you check codes its a waste of time if the check engine light hasnt came on.
how long since a tuneup?
you probably have a tbi not a cpi, if so fuel pressure only needs to be 9 to 14 psi. a cpi needs 55 or so.
jsgold has great ideas but hes referring to a cpi not a tbi. tbi is throttle body injection youll have something that looks simaler to a carb. cpi is central
port injection 1 injector per cylinder.