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Thread: 1984 6.2 with Banks

  1. #1
    Join Date
    Sep 2022
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    Unhappy 1984 6.2 with Banks

    Hey folks, really new to this game. Need some help with my 6.2. New injectors and filter in a unknown mileage(shows 86k) 6.2 with banks. Was running ok now starts and idles well but misfire and blows white smoke when you rev it up. Even from fresh diesel. Compression is good. IP?

  2. #2
    Join Date
    Apr 2001
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    CA
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    Welcome aboard!

    Good cold starts and clean idle is usually the first indicator of a good IP. What is your fuel pressure? It should be 4-8 PSI at idle, and never below zero under any load. A bad lift pump will cause what you are seeing. It could be the IP, but there are other more likely suspects. Also verify the timing order. It has a couple lines that can be swapped at the pump and still fit, and untidy lines over the valve covers may indicate a mix-up (or lines on the wrong cylinders, or the wrong lines, they are cylinder-specific, and should align nearly perfect before tightening).
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  3. #3
    Join Date
    Sep 2022
    Location
    Canada
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    Default Thanks for quick reply

    Quote Originally Posted by DmaxMaverick View Post
    Welcome aboard!

    Good cold starts and clean idle is usually the first indicator of a good IP. What is your fuel pressure? It should be 4-8 PSI at idle, and never below zero under any load. A bad lift pump will cause what you are seeing. It could be the IP, but there are other more likely suspects. Also verify the timing order. It has a couple lines that can be swapped at the pump and still fit, and untidy lines over the valve covers may indicate a mix-up (or lines on the wrong cylinders, or the wrong lines, they are cylinder-specific, and should align nearly perfect before tightening).

    Sorry for late reply, had some admin issues with page. Pretty sure fuel lines are ok but will check pressure. Forgot to mention it starts but never without the glow plugs. They are jenky wired into a switch from previous owner. If its warm should it need glow plugs? Shouldnt the inhibitor shut them down?

  4. #4
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    Apr 2001
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    CA
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    The glow cycle inhibitor only inhibits automatic cycling. A manual switch (should be) wired to the relay, OEM or otherwise, would force power to the plugs, regardless of what the inhibitor is doing. I recommend a bypass of some sort, even if you never use it. The "jenky wired" switch may indicate a problem had by the PO, perhaps what you're seeing. Some start without a GP cycle, but many/most won't in moderate temperatures. My 85 never needed GP's during the summer for a "cold" start, even in the early morning, but mine is the only one I've met that starts as easy. This, at near 600K, through 3 IP's, several lift pumps, head gaskets, etc, and the starting habits never changed. My 1995 6.5 would need GP's for a restart in a Phoenix July at high noon. I don't know why some do and some don't. There's a lot of variables to consider.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  5. #5
    Join Date
    Sep 2022
    Location
    Canada
    Posts
    3

    Default Idles/misfires under higher RPM

    Quote Originally Posted by DmaxMaverick View Post
    The glow cycle inhibitor only inhibits automatic cycling. A manual switch (should be) wired to the relay, OEM or otherwise, would force power to the plugs, regardless of what the inhibitor is doing. I recommend a bypass of some sort, even if you never use it. The "jenky wired" switch may indicate a problem had by the PO, perhaps what you're seeing. Some start without a GP cycle, but many/most won't in moderate temperatures. My 85 never needed GP's during the summer for a "cold" start, even in the early morning, but mine is the only one I've met that starts as easy. This, at near 600K, through 3 IP's, several lift pumps, head gaskets, etc, and the starting habits never changed. My 1995 6.5 would need GP's for a restart in a Phoenix July at high noon. I don't know why some do and some don't. There's a lot of variables to consider.

    Thank you so much, lots of work ahead. That is good news I think but we will see how the pressure check goes and lift pump diagnosis. What is the “PO”?

  6. #6
    Join Date
    Dec 2003
    Location
    Yukon Canada
    Posts
    1,460

    Default

    Previous Owner
    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

  7. #7
    Join Date
    Jul 2020
    Location
    Montana
    Posts
    385

    Default

    Before dropping cash, you could try advancing the timing on the injection pump.

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