Car wont start again

1990 buick lesabre 3.8 91k miles. Problem started about 3 weeks ago while driving car died and would not restart just cranks towed to the chevy dealer.Dealer put in a new cranksensor, starter and coil pack spent $350 and picked up car up drove home did the same thing. back at dealer they said every things checks out fine but car would not start for them. after an 1 or 2 hours looking over the car the car started right up and ran fine for them they said it could be a short somewhere but they they cannot find anything wrong with the car. Car ran fine for about 2 weeks and this morning backing out of garage the car died again and now just cranks again. I do not know what to do at this point but i need the car running any ideas would be helpful.I looked to see if there was any loose conections anywhere but every thing looks and feels tight .thanks…

SORRY. Just wanted to clear up first sentence car has a 3.8 engine with 91k miles

How could everything check out, and it not start? They took you for $350, and didn’t fix the problem? Did they check for fuel pressure when it wouldn’t start? Did they say that was OK? These cars are easy to check fuel pressure with a test port on the fuel rail. I bought my first fuel pressure gauge for a similar car. Also, did they check the ignition module? This is mounted on the fire wall. Did they just throw some parts at it and shrug?

I’m as exasperated as BustedKnuckles, I would never want to hear “we can’t find the problem” from a mechanic unless he wanted the benefit of my parade ground voice projection and military honed vocabulary.

Time for a rewind on this one and you’re at the perfect juncture to eliminating some of the possible problems since the car won’t start at the moment. You may not determine what the problem is, but you may be able establish what it isn’t. An internal combustion engine only needs fuel, compression and an ignition spark somewhere adjacent to the compression top stroke of the engine to work. You don’t mention any problems when the car is actually running so I’ll assume that at some point, though intermittently, you have all 3 of these pre-requisites.

Compression wouldn’t be variable enough to cause these symptoms so you can eliminate that. Likewise the likelihood of ignition timing moving enough to stop / start the engine is doubtful.

Therefore start with ignition functionality since it’s the simplest, pull one or 2 plugs and ground them on the engine block while someone turns the engine and check for spark at the plugs. If you have spark, you know the problem is fuel, if you have no spark it’s ignition.

Both of these systems have a check sequence to determine the problem including the fuel pump, camshaft position sensor, PCM, ICM…and on…

If you determine which of the systems is not working, it’ll make diagnosis easier.

It could be a poor, intermittent, wire connection. Often, a wiring connection can be improved just by disconnecting and reconnecting the electrical connectors. So, disconnect and reconnect all the electrical connectors in the engine compartment; especially, the ones to the ignition system, coil, etc.

Not that I’ve got fuel pumps on the brain lately but it sure sounds like a typical fuel pump problem. Do you hear the pump running for a few seconds when you turn the key. Fairly easy to diagnose with a $50 fuel pressure tester so if the dealer was unable to do it, they either aren’t taking you seriously because of the vehicle age, or draw your own conclusion. I’d go someplace else but it has to be doing it.