7.3 idi injection pump air lock, Or something worse?

Discussion in '6.9L IH & 7.3L IDI Diesels' started by ConstantVigilance, Dec 30, 2016.

  1. ConstantVigilance

    ConstantVigilance Registered User

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    Thank you for the detailed reply. It's been frustrating as anyone who does there own wrenching has experienced.

    Gonna head out today and see if the ATF worked. Then will remove it.
     
  2. ConstantVigilance

    ConstantVigilance Registered User

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    Update:. Still no start. Will pull IP and "bench test". .

    Will report back with results.

    Thanks again
     
  3. ConstantVigilance

    ConstantVigilance Registered User

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    Update, before I remove IP:

    I removed the lid again and cranked the motor. I can see the flyweights turning.

    I took a short video of me poking around under the cap: I'm wondering if you can tell if things are too loose inside there.

    Also, I ask a question about timing:. There is a bolt missing from the mounting points. That is, I think there are 3 studs that mount the IP, and the one on the passenger side is missing a nut. I saw a video where the IP timing is adjusted with this bolt. If it's missing, can that screw up things? Note: I can't move the IP. It's secure in place.

    Lastly: (this may very well be an additional problem) After I filled my filter with ATF, it didnt just come out the top of the IP, but it also came out of the return line on the driver's side. I had the line unplugged, sense I had the cap off, and that's when I noticed the ATF fluid.

    I'll post a video link (Google drive) or figure out how to up load it. The video is mostly to show you how loose the internals under the cap are.

    Thank you very much for your help thus far. If I can avoid removing the IP, that would be golden.
     
  4. ConstantVigilance

    ConstantVigilance Registered User

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  5. Agnem

    Agnem Using the Force! Staff Member Supporting Member

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    I feel like your being led down a bad road here. Sadly, the methodology has been corrupted by many different things happening, and a lot of potential problems have been introduced. Let's look at the facts as we know them.

    1) truck ran fine before you removed the injection lines (to service the glow plugs?)
    2) Known air leak at the fuel heater.
    3) bubbles forming at injector line outlets.
    4) Good return fuel from pump return fitting, indicating that the pump is moving fuel through it (no blocked inlet filter or primary pump failure, drive shaft intact and pump is rotating).
    5) Top cover has now been removed and reinstalled.

    You mentioned a couple of things that make me wonder. Why did you remove the injection lines to do the glow plugs? Most folks can get that job done without messing with them. Have you measured your fuel pressure at the pump inlet while cranking? You've done a lot of changes that affect fuel supply. Have you taken the injection lines off of the pump, and looked for fuel there? The pump does not put out gobs of fuel, and it can take a while to fill the lines. Don't assume that no bubbles means no fuel is moving. In my opinion, taking the pump off will only serve to screw up your timing and potentially introduce new problems. Is the shut off solenoid operating now? You started with a fairly simple problem. Honestly, I'm not sure where your at now.
     
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  6. Agnem

    Agnem Using the Force! Staff Member Supporting Member

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    Just watched your video. You need to understand that EVERY TIME you open up your fuel system, return, supply, or injection pump, your are ALLOWING THE FUEL FILTER TO DRAIN BACK INTO THE TANK. That means a ton of cranking just to get fuel to the pump! Seal the system and keep it sealed! Everything looks normal under the cover. If your pump is old, that cover gasket won't seal well. Call me to get a new one.
     
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  7. pelky350

    pelky350 Full Access Member

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    Idi performance pump works well! I got the 90cc pump and injectors from him truck runs like new now!
     
  8. ConstantVigilance

    ConstantVigilance Registered User

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    Agnes: thank you for your response and interest.

    As for why I removed the lines: simply didn't know any better.

    I have removed one injection line from the pump and saw nothing.

    I will do the following:
    Put cap back on
    Remove a few IP lines and watch for fuel.
    Reseal the system, but first fill the filter with fuel.

    I have good batteries and will put on a 40amp charger for 2 minutes between 20 second cranking.

    I suppose I should put a nut on that stud (the missing one I described above).

    I feel like there could be so many variables that it will be difficult to diagnose the problem.
     
  9. ConstantVigilance

    ConstantVigilance Registered User

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    Update:. I have the bleeder on top of IP going into a bucket and the return line (normally what the bleeder is plugged into) going into a different container. Both have fuel coming out upon cranking.

    I removed the closest 4 IP lines and began cranking. On the 4th or 5th cranking I noticed a dribble of fuel coming out of one of the IP line outlets. Specifically, cylinder 4 injector port (going to the 2nd cylinder from front, drivers side).

    It's not much, but it's more then ive seen thus far.

    I still have fuel coming out the top of the filter. This is a new development and has been getting worse.

    I'm going to keep cranking away.
     
  10. FORDF250HDXLT

    FORDF250HDXLT atlasmu'teget Supporting Member

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    you can't leave any fuel leaks.if you have a fuel leak,the fuel drains back.leaving a leak in the fuel system and trying to prime it,is like doggy peddling up Niagara Falls......your not gunna win.:D

    if your fuel heater is leaking,you should plug it with a pipe plug.

    [​IMG]


    Click Me: 7.3 Fuel Heater Delete Pipe Plug
     
  11. ConstantVigilance

    ConstantVigilance Registered User

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    Ok. I'm going to follow the directions in the link you sent me. I suppose up in Northern California it doesn't get cold enough for that heater anyway. Reading the thread sounds like I never really use it.

    I'll probably crank the motor over a little bit longer to see if I can get more fuel out and then disassemble the filter and fix that leak.

    Thank you so much for everyone's replies and help. I will give you an update as soon as I can
     
  12. ConstantVigilance

    ConstantVigilance Registered User

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    UPDATE:

    I "fixed" the leak at the fuel heater terminal (I just copied what, Stang65fst, did and JB Welded a plug into it).

    Yesterday I tried bleeding the IP again, this time two different ways: First, with everything hooked up but I left 4 IP lines off (the top 4, that are easiest to reach). I saw nothing at the outlets.

    I then plugged off the fuel return line at the filter. I read that this is common practice anyway, and sense I was getting a lot of fuel from that line, I figured maybe plugging it off would increase the pressure on the IP enough to get it primed.

    I was (am) also getting fuel coming out of the return line were the IP bleed line plugs into. (It's leaking at the plastic part where it sits above the injector - not coming out of the top like they say would happen if the injector was getting fuel) So, by running a line from the top of the IP into a bottle, I wouldn't have the leak I had before... Now, with the Filter Bleed line and the IP bleed line taken car of, I tried priming the IP. Still, I have those 4 IP lines opened at the IP.

    Still nothing coming out of the IP. I have a steady stream of fuel going to the bottle from the IP bleeder. No air.

    I was told by a "guy I know" to spray ether into the motor until it starts and than spray it every few seconds... this will pull the air out of the "locked" IP. I told him thanks, but have read on this forum that its not healthy for the idi.

    I'm running out of combinations of how to start this thing.

    I wonder: i can hear the valve on the IP clicking when i apply power to it, but the engine harness I'm using is off an Automatic truck. Could there be some other reason the IP wont flow? I did us a "jumper" on the clutch neutral switch that I pulled off a manual truck. I understand that that is all it takes to "trick" the truck.

    ((I'm using a 93 motor out of a manual, in 92 frame and using that same 92's engine harness - which was an automatic before the PO did a manual swap - and the cab is off a FUEL INJECTED 1994 f250 manual))

    I will pull the bleeder valve and see if its obstructed, I guess - but because i'm getting plenty of fuel, I'm sure its fine.

    Thanks for the feedback, thus far, and any help is very appreciated. ((sorry to drop the fuel injected part on everyone - it never really dawned on me that it could be relevant))
     
  13. Macrobb

    Macrobb Full Access Member

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    Are you doing all your bleeding with the throttle floored?
     
  14. ConstantVigilance

    ConstantVigilance Registered User

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    Yes. I've hooked up something similar to the video.
     
  15. ConstantVigilance

    ConstantVigilance Registered User

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    Update:

    This morning I spoke with a mechanic from John Deer: he happens to have owned a 7.3 idi for years and is the local John Deer go-to guy for diesels.

    We spoke for about 20 minutes and he ran through all the same questions that you all have asked me here.

    He did have one suggestion: He says that there may be two different sources for powering the IP's metering valve. That is to say, when you turn the ignition on and when your cranking. He wasn't sure, but given that the cab is from a fuel injected truck, it wouldn't hurt to rig up a constant 12v source. So I did that. Same results.

    Basically, I'm getting good fuel, no air, from the filter to the pump - and then out of the pump.

    I've got the fuel filter return line capped off. I have the IP bleeder going into a glass jar. I have the two, unused, nipples on the return line rail capped off.

    I'm getting a good flow into the glass jar, and no bubbles. I have the closest (top four) IP injectors removed from the IP, and I'm watching for some fuel there. I get good pressure when I push the schrader valve ( that is, when I stop cranking the motor and push the valve, the fuel spurts out a few inchs for a good 2-3 seconds at least, then trickles )

    Nothing.

    I'm afraid, somehow, between the time I ran the motor after purchasing the truck, to now, a year later, the IP has malfunctioned.

    For about 15 seconds I debated on rebuilding it myself. But, I'll look into purchasing one. I've seen a few threads on this sit that discuses in depth the different IP's available.

    I'll wait a little longer (sense I need to raise the funds anyway) to see if anyone else has any ideas.

    Thank you everyone for taking time out of your day and helping me out.
     

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