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7.3 miss

Discussion in '6.9L IH & 7.3L IDI Diesels' started by Plowboy13, Feb 13, 2020.

  1. Plowboy13

    Plowboy13 Registered User

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    I have a 92 super duty, the truck only has 41k original miles, so I had a leaky return line on one of the injectors. Replaced all the return lines and caps on the injectors along with new orings . Now I have a noticable miss. Cracked all the injector lines, and all change the engine. I dont see any leaks on or around the return lines and am at a loss.
     
    Selahdoor likes this.
  2. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    How long did you let it run? You may still have air in your fuel system.
     
  3. Vern

    Vern Full Access Member

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    Had you made efforts to prevent crud entering? I'm in a somewhat similar situation. But, had some progress when it got good and hot plowing the other day, now comes out of it after a while like it did before injector work.
     
  4. Plowboy13

    Plowboy13 Registered User

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    I ran it hard pulling a loaded gooseneck and a few times since but to no avail. I had one friend tell me about a small plunger/ check valve in the top of the injection pump that are known to go bad?
     
  5. frankenwrench

    frankenwrench overkill is under rated!

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    The fitting going from the top of the ip back to the filter housing has a check valve. Just plugged mine up a few weeks ago and helped my similar issue. Surely more will chime in with other ideas...
     
  6. cozinsky

    cozinsky Registered User

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    A few years ago I had an old can of fuel that I dumped into my tank. Almost immediately it began smoking and missing. Even after switching to the other tank it still ran rough and smoked. I drove it several miles but it didn't come out of it. Based on the suggestion from a member on another forum I go to: I took a new fuel filter and filled it with automatic transmission fluid. Started the engine and ran it until it stopped surging and smoothed out, then shut it off and let it set overnight. The next morning it ran perfect and I haven't had any issues since. You may have a sticking or dirty injector. ATF is high in detergent and works great at cleaning out the system.
     
    Last edited: Feb 14, 2020
  7. Plowboy13

    Plowboy13 Registered User

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    Thanks I'll give it a try!
     
  8. Vern

    Vern Full Access Member

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    On top of the pump is a solenoid actuated valve that's intended to advance the timing under normal circumstances because when closed it restricts return flow and build housing pressure to move the timing piston and rotate the camp. Air is bled past it too but that should have happened sufficiently if the engine is running, no?
     
  9. Plowboy13

    Plowboy13 Registered User

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    Well ran it really hard over the weekend, got it good and hot and now it seems to have lost the miss, so I'm thinking it just had trapped air somewhere, thanks for all the help
     

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