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Truck cranks runs fine till warms up then

Discussion in '6.9L IH & 7.3L IDI Diesels' started by Ray-F250, Feb 11, 2019.

  1. Ray-F250

    Ray-F250 Registered User

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    my 94 7.3 runs fine cold then it dies like it’s not getting fuel it’ll run ruff and loose power after around 20 miles any thoughts
     
  2. DrCharles

    DrCharles Full Access Member

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    How many miles on the injection pump? Are there any problems starting it when hot?
     
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  3. Oledirtypearl86

    Oledirtypearl86 Full Access Member

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    X2 what drcharles said kinda sounds like with the heat your IP gets heat soaked and won't push the fuel needed
     
  4. Ray-F250

    Ray-F250 Registered User

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    It does turn over a few times before it cranks when it’s warm but will crank it is kinda sluggish trying to crank it
     
  5. Ray-F250

    Ray-F250 Registered User

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    The truck is a turbo as well I was wondering if some how it is getting air in the lines. What would be a good way to determine if it is the ip
     
  6. renjaminfrankln

    renjaminfrankln Supporting Member Supporting Member

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    Does it crank right up when cold?
     
  7. Ray-F250

    Ray-F250 Registered User

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    Yeah it has no problems cranking. It only has problems after it has been running for about 20 minutes or so then it wants to cut off when I let off the throttle pull over on the side of the road and it cranks back up it does take it a little longer to crank when this occurs though
     
  8. Ray-F250

    Ray-F250 Registered User

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    I have already changed fuel filter and dropped the tank to ensure that there is no blockage on screen
     
  9. renjaminfrankln

    renjaminfrankln Supporting Member Supporting Member

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    Sounds like an internal injection pump issue. As noted earlier a worn out one will act up when its hot.

    A leak in the fuel line allowing the pump to suck air would probably happen regardless if it is cold or hot. Before condemning the pump, you should check the fuel pressure at the filter head to make sure the lift pump is doing its job. To my knowledge when they wear out, they are not known for being worse when hot like the IP. But it won't cost you very much to buy/borrow/rent a gauge to test the pressure. Also would have saved you from dropping the tank.

    If you have to buy a new IP I recommend getting a rebuilt one from a shop that specializes in IDI's. Search here for vendors. I am in the middle of doing this job for the 2nd time because I cheaped out on a rebuilt IP from pensacola.
     
  10. Ray-F250

    Ray-F250 Registered User

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    Ok thanks what pressure reading should I get when I check the lift pump
     
  11. david85

    david85 Full Access Member

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    Throw 1L of transmission fluid in the tank. Better yet, fill the fuel filter with ATF, start if up and let it run for a minute before letting it sit overnight. Then take if for a 1-2 hour drive the next day.

    Stalling when the throttle is let off usually is the governor or metering pump sticking inside the injection pump. ATF can sometimes clean this out but you may still be in for a new pump eventually. In my case, I still got a few years out if it.
     
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  12. The_Josh_Bear

    The_Josh_Bear Full Access Member

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    I had a textbook hot-start IP issue and it never had anything to do with the engine running. I really doubt a running IP getting proper fuel flow would die on itself.

    First I would check fuel pressure while running, the IP *will* pull it's own fuel but that's not a good way to make it around town.
    Also, make sure your idle RPM is high enough. These are mechanically injected engines, its possible for the idle to be so low the engine won't run when hot, though I haven't heard of it yet.

    As @david85 said a sticking metering valve is a semi-common issue with pumps that have sat for a long time. The ATF/Diesel Kleen treatment in the fuel filter works very well in this case.
     

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