Hello

Discussion in '6.9L IH & 7.3L IDI Diesels' started by Recon8993, Jan 13, 2018.

  1. Recon8993

    Recon8993 Registered User

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    Hey everyone. Just joined forum. I have a 86 Ford F-250 6.9 idi. Im having a rough idle and stalling after engine warms up. I’ve done a return line kit and have no leaks. Not sure what next step is to diagnose if it’s I/P or something else. No water in system and new fuel filter
     
  2. FordIDIot

    FordIDIot Supporting Member Supporting Member

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    welcome! i love bull nose trucks. best dash lights and coolest grills!

    it is stalling at idle once warmed up? have you checked fuel pressure to the filter?

    can you explain more about a rough idle? have you tried cracking open 1 injection line at a time to see if you have one bad injector?\


    sounds more like IP to me.

    if it wont start after being warm you can try to pour some water over the IP. it will cause the aluminum case to shrink slightly getting a better seal on the rotor inside. but this being winter time im not sure if it can get hot enough to cause that problem.

     
  3. icanfixall

    icanfixall Official GMM hand model

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    Welcome to the forum. What you described sonds like the pump may have som varnise built up in it. First off never allow fuel tanks to reach the 1/4 level because most tank suction lines are broken off so they "run out of fuel" at the 1/4 level. Thats how high the broken suction line sits off the bottom of the tank.
    Now please understand ANY injector or injection pump is worn nearly to the end when mileage on either reaches 125,000 to 150,000 miles. Some may boat they are running fine with over 200,000 miles on these fuel parts but boasting is just that.
    Please read the Hall of Shame forum BEFORE YOU BUY from the cheapest ebay seller. This forum knows who sells the GOOD STUFF and we support them.
     
  4. Recon8993

    Recon8993 Registered User

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    Well. This is how it goes every day. Cold start... it starts.. once I drive it about 5 to 10 minutes and it warms up. It will try to stall. I push the gas and it will still stall out. It will take about 30 seconds of turning it over and having gas pushed all the way down.
    This will continue to happen
     
  5. Recon8993

    Recon8993 Registered User

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    My parents found it at an estate sale and picked it up for me since they know how I love these old ford idi diesels. The plus is they got it for $1500. Great interior, ok exterior.
     
  6. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    Not saying that this is the problem, but maybe the lift pump is weak. I'm thinking that maybe it just can't keep up with the fuel demand from the engine. Does the problem exist if you just let the truck sit and idle?
     
  7. FordIDIot

    FordIDIot Supporting Member Supporting Member

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    yeah sounds like the lift pump may not be able to keep up with the IP.

    check your oil level. is it higher than normal? feel thinner than it should?

    you may have a bad pump diaphram. letting fuel leak into engine oil
     
  8. Macrobb

    Macrobb Full Access Member

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    It's probably getting some air in the lines as well... dying even with throttle is usually that - the IP will pull fuel from the tank, even if the lift pump can't "push" it... but only if there is no air getting in the lines.

    I'd be looking from the lift pump to the tank; I'd probably replace the lift pump as well; it'll help with bleeding and cranking, but will probably NOT solve your problem.

    I also don't get you guys blaiming the IP... I've had plenty of sketchy, worn out IPs, and none have done that... if it were gunked up, it might respond stickily, die as you let off on the throttle from a high RPM... but flooring it will always shove things open enough to keep it from dying.
    If it were really stuck tight, it would die and would never fire again.
     
  9. Recon8993

    Recon8993 Registered User

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    Ok..update. I installed a clear line between filter and return line. And just parked running air bubbles in the line. Took for a drive and it had massive small air bubbles and started to try and stall. Return line kit I installed and around the injectors is dry. Also see air bubbles going backwards too
     
  10. Macrobb

    Macrobb Full Access Member

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    Ignore anything past the lift pump - with the engine running, it would push fuel /out/, not leak air /in/. Fix the leak which is somewhere before the lift pump.

    Have you replaced the loop of fuel line going from the frame rail to the lift pump?
     
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  11. madpogue

    madpogue Full Access Member

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    The line doesn't go directly from the frame rail to the lift pump. It goes to the water separator first. I've heard that's notorious for air intrusion.

    Option - find a combination filter/separator that fits your existing filter head, or swap to a 7.3 filter head. Then you _would_ run a line right from the frame rail to the lift pump, and bypass/decommission the OEM separator.
     
  12. FordIDIot

    FordIDIot Supporting Member Supporting Member

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    thats not right. it should go from hard line on frame rail (from fuel tank) to the lift pump via a small rubber line. then the hard line from the lift pump goes to the filter head. from there the other hardline goes to the IP.

     
  13. madpogue

    madpogue Full Access Member

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    ^^^^^ That's only on the 7.3s.
     
  14. Macrobb

    Macrobb Full Access Member

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    You are right about the 6.9 vs 7.3. I forgot; pretty sure there is a similar line mounted to the passenger frame rail by the engine, though...
     
  15. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    While the hard line is different, it looks the same at the end you're talking about Macrobb. They both had the rubber fuel line making a loop before the lift pump.
     

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