Gas on Spark Plugs

mikey334mikey334 Member Posts: 4
edited October 2015 in Pontiac
I have a 2004 Pontiac Grand Prix GT GM 3.8 (Series III). My car has been Misfiring and idling rough. Code scanner told me i had a "Cylinder 3 Misfire". Cylinder 3 and Cylinder 1 Spark plugs are FOULED/DRY BLACK and the other 4 Spark Plugs have GAS ON THEM. What could be my problem?

The spark Plug and wires are new. Bought a new coil pack for Cylinder 3, still didn't change anything (Same code, Cars till running the same). So i was told to switch the coil packs around and that seemed to do the trick. car started of running smooth about 5 seconds then would start back misfring and running rough at idle. I also switched fuel injectors around still did do anything. Any help apprecaited.


  • imidazol97imidazol97 Crossroads of America I70 & I75 Member Posts: 26,497
    Check the fuel pressure regulator. There are videos on youtube showing how to pull off the vacuum line. If you get raw fuel coming out of the end of the line or a heavy gas smell, run the car with the line off. You can plug the line with a golf tee or pencil. After a few minutes of idling see if you get fuel coming out of regular because of a cracked diaphragm inside. That would put a lot of extra fuel into the intake manifold that the engine can't compensate for with extra air.

    If your engine runs better with vacuum hose off and plugged, that would be a good clue.

    FPR can be replaced with parts from aftermarket stores or

    Good luck!

    2014 Malibu 2LT, 2015 Cruze 2LT,

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