http://www.2carpros.com/articles/car-cranks-but-wont-start

Next time it refuses to start don't wait for it to make up its mind-do below immediately to determine if its fuel or spark problem

Get a helper disconnect a sparkplug wire or 2 and ground it to the engine atleast 3/16 away from ground-have helper crank engine over-do you have a snapping blue spark? If so-you have a fuel related problem, Do you hear the fuel pump come On when you turn key on? If not check fuel pump fuse and fuel pump relay if okay-check the fuel pressure to rule out the fuel filter/fuel pump/pressure regulator and listen to the injector/s are they pulsing or hook up a noid light. No snapping blue spark continue to troubleshoot the ignition system-power input to the coil/coil packs,coil's resistances,cap and rotor,distributor pick-up coil, ignition control module, cam and crank sensors and computer Note: If it doesn't apply disregard it and keep testing

Answered by rasmataz
68 questions asked

My 90 Lumina 3.1 was having similar problems and it ended up being 2 bad fuel injectors. you can check this by taking off the plenum and removing the electrical connectors for the injectors. On the injector itself are two metal prongs. Using an Ohm Meter touch 1 prong with the positive line and the other with the negative line. Each injector should read between 11 and 13 ohms. If it reads 7.5 to 10.5 it will cause some issues but wont necessarily make your car not run but if it reads anything less your car will stall. I had also replaced the brain or ECM. While changing the injectors I replaced all the sensors in that area and the crankshaft position sensor which is located on the back side of the block to the side and down from the oxygen sensor under the spark plug on the passenger side. I used a mirror to locate it. It is easier to remove the alternator to get to it but not necessary. Be careful if you do change this sensor as it fits tightly and is known to break apart. The new ones have metal clips but the old original ones are plastic. I replaces this sensor, the oxygen sensor, the throttle position sensor, and coolant temperature sensor. I figured if I'm taking it off I'm putting on a new one! Good luck and I hope this helps!

Answered by tinkergirl
5 questions asked

Ok. I have cleaned the IAC OHMed all injectors. Tested EGR, 02 sensor, temp sending unit and control sensor. Still starts fine when cold and idles great then just dies when car warms up. Got good spark and great fuel pressure. What now

Response from tshort66
1 question asked

Could it be a defaulting PCM.. I sure hope not..lol

Response from tshort66
1 question asked

I agree. it could be your ECM/PCM. They are very easy to change but mine cost 100 + a core charge. Make sure it is this before you purchase a new one and put it in, because once you change it, you cannot return it. You also have to make sure you put the memory stick from your old one and put it into the new one if you end up having to replace it.

Answered by tinkergirl
5 questions asked