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350 gas - diesels when switched off

Discussion in 'The Garage' started by dontoe, Mar 22, 2005.

  1. dontoe

    dontoe 3/4 ton status GMOTM Winner

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    My best freinds Chevy P/U diesels when he switches it off. He said it stopped when he switched to Mid-grade gasoline.

    Never encounterd this type of problem before. What'cha think?

    Found this in a search................is that it other than timing!

     
  2. diesel4me

    diesel4me 1 ton status Premium Member

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    Sounds like me!

    I think that was ME who posted that last year sometime!:blush:

    Other than what that post listed,a valve or carbon deposits can glow red hot and ignite the fuel even when the spark plugs stop firing when you turn the ignition off...but if thats the case you will get pinging under load or acceleration too..and its hard on the pistons and valves when that occurs..

    I'd say 90% of the time its timing too far advanced,idle speed too high,or the idle stop solenoid not working,( if it has one)-and someone turned the idle speed up to compensate,that encourages dieseling...

    My 79 C10 has an Edelbrock carb,it has no idle solenoid--I turned the idle speed up slightly during the cold winter to prevent stalling--now that its warmer,its idling a bit too high,and it started "running on" after I shut off the ignition--I turned the idle speed down about 100 RPM so it idles at 700 RPM in drive--no more dieseling..Til I adjusted it,I just left it in drive and shut it off,it wouldnt diesel then either--but I almost forgot to put it in "Park" a few times--almost ran my foot over when it started rolling away!..:blush:
     
  3. big jimmy 91

    big jimmy 91 1/2 ton status

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    As was already said , carbon build up.

    You can get some carb./combustion chamber cleaner from a parts store...
    Or use the back yard method of pouring water down the carb when hot , just not so much as to hyro lock it(while reving it up,not allowing it to stall)
    Cleaning or changing plugs is recomended after either method :grin:
     
  4. Z3PR

    Z3PR Banned

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    Run a can of 44K through it and see if that helps.
     
  5. dontoe

    dontoe 3/4 ton status GMOTM Winner

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    Thank you gentlemen!!!:grin:
     
  6. R72K5

    R72K5 Banned

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    idle speed is too high, or timing is too advanced

    one of the two is the cause 99% of the time

    fix it ASAP,, it will start damaging the engine if you let it continue to occur,....
     

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