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1991 F250 7.3 no start

Discussion in '6.9L IH & 7.3L IDI Diesels' started by David A Hodson, May 25, 2019.

  1. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    Should be coming out of the pump, the injectors only should account for 5-10% of the return fuel, the rest should be the pump’s return.
     
  2. Selahdoor

    Selahdoor Full Access Member

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    Thank you.

    So apparently I DO have a problem with the IP, even though my engine does run. LOL
     
  3. David A Hodson

    David A Hodson Registered User

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    Well we had the engine running half way decent and a return hose came off so I shut it down and now I’m back to square one. About ready to go get a new pump and injectors and start from scratch.
     
  4. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    So it won’t start now after the return line came off?
     
  5. David A Hodson

    David A Hodson Registered User

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    Nope not even on ether which is how I got it running earlier. This truck has been a real pain since he got it. It had sat for almost 10 years due to a bad lift pump
     
  6. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    Is the return line from the filter plugged still? If it won’t start on ether it’s not getting fuel. How quick is it cranking?
     
  7. David A Hodson

    David A Hodson Registered User

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    Wes
    To start it cranks fairly good with the charger on it.
    Yes the line from the filter to the injector return cap is still pinched off
     
  8. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    If you have a tach, you need at least 150 rpms to make cranking fuel, 250 rpms is more what I like to see. You may have a weak lift pump, you could put an electric fuel pump on to elimate the priming issue. Takes a lot less cranking to get air out with an electric fuel pump.

    How much fuel do you have in the tank you are pulling from? If it’s aeound a quarter tank, add five gallons and try again. The pickups in the tank tend to break off and start sucking air at 1/4 tank. If you want the pump gone through, and new injectors, just let me know ;Sweet
     
  9. David A Hodson

    David A Hodson Registered User

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    I have at least 200 rpms and it’s a new lift pump ( I know it could still be weak ) I’m starting to think the inj pump is going out.
    I want to put all new stuff on with an electric pump.
     
  10. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    That’s plenty of rpm, it could be the metering valve in the injection pump is stuck shut. You could try pulling the fuel filter off and filling with atf. The thicker fluid is pumped easier by the injection pump, and the detergents in the atf can help free things up if it’s been sitting a long time. Worth a shot, would you want your current pump rebuilt or have one of my cores rebuilt and you send back your current pump?
     
  11. David A Hodson

    David A Hodson Registered User

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    We have a diesel shop close so when the boy gets the cash we’ll pull everything and take it too them. Thanks for the offer though
     
  12. reset2

    reset2 Full Access Member

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    Read around the site. There are a lot of really knowledgeable people at oil burners and a local shop might not know the ins and outside of these IDIs


    Sent from my SM-G935V using Tapatalk
     
  13. David A Hodson

    David A Hodson Registered User

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    Well I finally woke up and figured out the problem. After playing with it all weekend doing this test and that test we found out we wasn’t getting fuel from the tank so we used a clean diesel fuel can and a electric pump and it would run for a little bit. Couldn’t figure out why. Blew air towards the tank on supply line and heard a pop around she selector valve. Ok bad valve but it didn’t dawn on me till today that if the supply side of valve was closed off then the return side would be also. Put a different valve on the truck and it fired right up and ran great better than it ever has. So it’s on the road till next time. Lol.

    Thanks for all the help
     
  14. reset2

    reset2 Full Access Member

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    Success. The smell of burnt diesel fuel in the morning is the sweetest when the problem is solved.

    Sent from my SM-G935V using Tapatalk
     

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