Oldsmobile/Buick Repair: 94 buick regal not starting, coolant temperature sensor, oil pressure switch

Question
My daughter has a 1995 Buick Regal Custom. The car cranks fine in cool weather. After it has been driven during warm or hot weather it will not even turn over until the car sits for an hour or so. Coukd you give me an idea of what might be happening. Thanks

Answer
Hi Greg,
By "Turn Over"...do you mean it won't even rotate the crankshaft, or do you mean it cranks over, but won't hit a lick?

If you mean the second scenario, you may need a coolant temperature sensor.
See  http://www.chevytalk.org/threads/showthreaded.php?Cat=0&Number=1366279

If there is no spark, there could be an intermittent open in the ignition circuit, but I would expect it to die occasionally if that were the case.

Another possibility is the fuel pump relay is not working and the pump is being operated by the oil pressure switch, which runs the fuel pump after oil pressure builds up. The pressure could be building quicker when the oil is cooler.
Check to see if you can hear the pump in the gas tank running when the key is turned to run. The pump should humm for about three seconds, then shut off, unless the engine is cranking over.

Van