I have an 04 Impala, 3.4, 123,000 miles. My wife stopped at the babysitter's house and the car died violently. It now cranks but will not start. I replaced the fuel filter and the pump because I could not hear the pump running when I turned the key on. I also had the pump relay checked and it's good. After replacing the pump, I tried to start it and nothing. Still couldn't hear the pump. I removed the pump relay and jumped a wire across two leads and was able to make the pump run and pressurize the system. I put the relay back on, cranked it and it started but only ran for a short time and it was very rough. It backfired and died. Then I replaced the crankshaft position sensor. I still can't hear the pump run. I pressurized the system again and cranked it and it started. It ran really smooth until it died. Something is keeping the pump from running and I can't figure out what it is. I need some help please!

I'm thinking I will replace the camshaft position sensor next. I was told that if the cam sensor is not sending a signal, the pump will not come on. I checked the cam sensor with a test light. I'm not good with electronics but this is how I was told to do it. Turn ignition on; attach test light clip to negative battery post; touch light to the red wire on the sensor and it should light up if it's getting power (did this and it lit up); then touch light to other wire (can't remember color, but not the black one) and it should light up if the sensor is good (did this and it did not light up). I assume that means the sensor is bad. If someone has any other idea, please let me know. Or if I did this test wrong or if my assumption is wrong that the sensor is bad, please let me know that also. I appreciate any advice anyone may be able to give.

Normally a bad cam sensor will set a code. Guess work is going to bury you here, get a factory manual or wiring diagram and track this down using the proper diagnostics.

Well, I find myself tired of messing with this and a little low on funds. I've decided to wait until next pay day to have someone else take a look at it. Once I get it fixed I'll post the solution.

I know you said the fuel pump relay checked OK (not sure how that was determined) but from your description it sure sounds like there could be a problem at the relay. I don't want to suggest you replace parts without diagnosising them though. I think even a Hanes manual will tell you which pin at the relay should be hot from the PCM for 2 seconds after key's ON and during cranking.

Also check all your fuses, ignition, PCM, fuel etc. Also you might try to see if you have spark at a least one plug wire. If your ignition module went totally out it wouldn't send a reference pulse to the PCM to keep the fuel pump (although that doesn't explain why fuel pump doesn't run when key is turned ON)

Try this it worked for me on a 99 S10 ,, unplug the ECM so it willl re set every thing back to defult wont reset till it runs a bet so if it wont run wont reset try it more than once if you have to !!