Question I've done a complete tune up on my truck plugs wires button cap pick up coil and coil. Truck ran great but when I parked it for the day and came back out next morning and it wouldn't start. I checked the firing and all was good. I pulled a plug and it was soaked in gas. I changed plugs again. Started right up and ran good throughout the day with shut offs and restarts. I parked it for the day again and next morning the same exact thing happened again. Overnight it gas soaked all plugs again. What makes it foul the plugs overnight???
Answer Hi Ashley,
All I can imagine is that the fuel pump may be continuing to run after you shut off the engine and over time the on-going pressure on the fuel rail is causing the injectors to leak overnight. I don't see how all the injectors could be stuck open and in any case they would be damaged if they were activated continuously for a minute or so by their driver wires being grounded. The power for the injectors should be removed in any case when the autoshutdown relay opens when the engine is shut down. So listen for the fuel pump to still be running when you shut down the engine. It is controlled by the pcm rather than by the ASD relay so it is possible that it hasn't been cut off.
I wonder otherwise if there is some sort of a temporary failure of the injector drivers/spark at initial start up but I can't believe that would soak the plugs.
Let me know what you find.
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