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Thread: 84 gmc 2500 g20 6.2

  1. #1
    Join Date
    Dec 2023
    Location
    Ma
    Posts
    3

    Default 84 gmc 2500 g20 6.2

    After cycling the glow plugs Multiple times when cold (48 degrees) the van will not start. If I plug in the block warmer it starts Automatically
    I have 12 + volts to the relay at the back of the driverside cylinder head but only 9 1/2 volts out to the glow plugs all 8 glow plugs have power to them but only 9 1/2 volts is that my problem? Any info would be appreciated

  2. #2
    Join Date
    Dec 2003
    Location
    Yukon Canada
    Posts
    1,621

    Default

    Test your glow plugs to see if they are any good
    90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews

  3. #3
    Join Date
    Apr 2001
    Location
    CA
    Posts
    13,575

    Default

    Welcome aboard!

    12V in and 9.5V out of a relay is a bad contact. It should carry full voltage. If that's the fact, there's too little juice to heat the plugs enough for a solo start. Easy starting with the block heater almost certainly confirms that.

    Your other thread in the Photo Forum, stating essentially the same as this thread, will be deleted.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  4. #4
    Join Date
    Dec 2023
    Location
    Ma
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    3

    Default

    I will be checking them. I was told they were just put in not even 2000 miles ago.
    But that doesn't mean anything he did use ac delco Ty

  5. #5
    Join Date
    Dec 2023
    Location
    Ma
    Posts
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    Default

    Thank you. I cleaned up some rusted connections and will be checking.
    To see if I have more voltage coming out of the relay I actually did not check the voltage. Because I got it running on a cold start with no plug in. Hopefully I fixed the problem. Ty

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