Edmunds Answers



  • drvette 12/17/11 10:48 pm PST

    Sounds like fuel, maybe.

    Get a pal to help, someone sit inside the vehicle with the door CLOSED.

    Open the gas cap, get him to turn the switch to the ON position, Not Start

    Listen for a humming sound, it should run a few seconds, then after getting full pressure built up, shut down..

    There is a TSB on your vehicle for the symptom you stated also.

    Bulletin No:041201

    Summary Description:

    Take the vehicle to the BEST GM dealer nearby, take bribery material with you, a sack of apples works well.
    Print the TSB number I listed if the fuel pump is not the culprit..


    Source: http://www.ownersite.com/TSB/tsbs.cfm/

  • zaken1 12/17/11 11:03 pm PST

    This is most likely caused by either a bad camshaft position sensor, or a bad crankshaft position sensor. If it is the cam position sensor; there will be no trigger pulses to the fuel injectors
    at the time when it won't start; (but you have to be careful about testing this; because there will be trigger pulses at the injectors when it does start). There is an inexpensive tool called a "noid light" which is sold at many parts stores. This tool clips onto the injector wiring, and flashes a light when there are trigger pulses.

    If the problem is the crankshaft position sensor; there will be no spark at the plugs when it doesn't start; but here again; there will be sparks at the plugs when it starts.
    If it is caused by a fuel supply problem; it is MUCH more likely to be caused by a defective fuel pump wiring harness than by a bad pump. Countless perfectly good fuel pumps have been trashed because of the GM fuel pump wiring harness problem. So I recommend buying and installing a new fuel pump wiring harness from a good parts store before assuming the pump is bad. It will cost MUCH less than a new pump. And don't forget to also replace the fuel filter.
    A cracked distributor rotor or distributor cap, or bad plug wires, or worn spark plugs can also cause such problems.


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