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How To Determine If Fuel Pump Is Rebuildable?

Discussion in 'Early CJ5 and CJ6 Tech' started by Eric, May 16, 2022.

  1. May 16, 2022
    Eric

    Eric Member

    CA
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    A sudden lack of fuel reaching the carburetor halted my attemt to drive off the trailer today. The first confirming test was to disconnect at carb and crank the engine... no gas. Okay, that was the second confirmation, the first being checking for fuel in the tank. I could see fuel in the pump (glass bowl) but it was not as high as usual. Removed fuel pump and filter (which I plumbed just in front of the pump) and tested the pump with a hose going into a tank of gas at similar level as pump. It tried, but never really drew much gas into its bowl. The action of the pump seems fine so I separated it and the diaphragm in the pump has no holes, but it does look checkered and old. Researching the rebuildability of this pump, I learned that some are rebuildable (pre 1963?) and some not (post). This is off a 1962-ish but I have no idea if it is the original pump. Is there a visual way to determine if mine is rebuildable?

    Follow-up questions assuming it is rebuildble: First, is this an easy task? Next, who sells good kits for these? And finally, is there something I am olverlooking in the diagnosis of a faulty fuel pump that might save me time and money? Thanks all!
     
  2. May 16, 2022
    Lockman

    Lockman OK.....Now I Get It . 2022 Sponsor 2021 Sponsor

    White City, NY 14617
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    Kaiser -Willys Jeep parts has the single action kit for $ 50. You can also buy a new pump from them for $65
    From their site :
    [​IMG]
     
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  3. May 16, 2022
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2022 Sponsor 2021 Sponsor

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    If it is a glass dome type, I've found that the dome gasket can be problematic. Worth double checking.

    Rebuilding is simple enough.

    But I've seen some recent fuel pumps that have the valves pressed/swaged into the body, and not replaceable.
     
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  4. May 16, 2022
    Eric

    Eric Member

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    Yes, glass dome type. There are no markings cast into the body, but there is a little aluminum tag with the circled AC logo and the numbers 572 G9 stamped on it. No idea what the numbers mean. I managed to take the pump apart (curiosity got the better of me) and miraculously got it back together awaiting a solution. Valves seem to function fine. I will check the gasket on the dome. Might have to make one. Thanks for the tip.
     
  5. May 16, 2022
    Oldpappy

    Oldpappy A.C. Fults - Curmudgeon at large 2022 Sponsor 2021 Sponsor

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    If you do buy a kit make sure the diaphragm is modern material that will stand up to modern fuels. There are a lot of cheap rebuild kits out there, but you get what you pay for.
     
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  6. May 16, 2022
    Howard Eisenhauer

    Howard Eisenhauer Super Moderator Staff Member

    Tantallon, Nova...
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  7. May 16, 2022
    zootin

    zootin Member

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  8. May 17, 2022
    Eric

    Eric Member

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    There are no casting numbers on the body of the pump. It does have a stamped tag on it. The tag has an AC logo on it. Is 572 the model number?
    tag.jpg
     
  9. May 17, 2022
    Eric

    Eric Member

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    Thanks. Your wise words have increased my caution as I rebuild parts. I have not yet found a kit that advertises that it will stand up to modern gas, though there are replacement pumps that do advertise thus. If they do not specify, I am inclined to believe they won't survive ethanol. I'm hoping to rebuild rather than replace because I am proud of the work I did installing a filter (inspired by you) and don't want to undo it if I don't have to. I'll keep looking.
     
  10. May 17, 2022
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
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    Or perhaps you could simply reach out and ask the suppliers if their products are compatible with modern ethanol fuels. Not really a difficult thing.
     
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  11. May 17, 2022
    Eric

    Eric Member

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    You are correct. I have done that a few times and two did not know and one vendor told me "probably not" so I am still moving down my list. Something will click soon. I tossed this out in case someone has recently dealt with this matter. Also to find out how to tell if the pump is rebuildable. I am learning a lot as I go. Thanks.
     
    Last edited: May 17, 2022
  12. May 17, 2022
    nickmil

    nickmil In mothballs.

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    Excellent! Many (most) do not, (which Is why I suggested it), so good on you for doing due diligence.
     
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  13. May 17, 2022
    scoutpilot

    scoutpilot Member

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    Possible problems diagnosis.

    Low fuel state.
    Vented fuel cap not venting creating excessive vacuum resistance to flow in the tank.
    Loose bowl bail. Allows air infiltration which reduces flow/pressure.
    Bad bowl gasket. Allows air infiltration which reduces flow/pressure.
    Loose connectors at the pump. Allows air infiltration which reduces flow/pressure.
    Loose screws around the mating flanges. Allows air infiltration which reduces flow/pressure.
    Trash/rust particles in the gas. This condition can cause blockage one or both of the valves in the pump.
    Rubber tube placed over straight-cut metal line with only one clamp. With only one worm clamp the rubber, especially if it is old, will bunch up in one spot and allow air infiltration which reduces flow/pressure.
    Old rubber tubing will dry out and develop cracks which allow air infiltration which reduces flow/pressure.
    Depending on the design of the filter this may be the issue.
    The tag would indicate yours is a unit produced under contract to AC by either Airtex or Kem. It likely has the pressed-in valves and perhaps one has come loose. These can be rebuilt but great care in the removal of the old to avoid damage to the body, and installation of the new ones.
    There is a step in the rebuild that, while absolutely critical to a necessary diaphragm pre-load, is rarely mentioned. The pump top must be initially placed on the bottom with the screws slightly loose. Chuck the loose (snug is okay) assembly by the pump arm tightly into a vise. Pull the pump back to a full stroke and hold it there while tightening the screws. Start point doesn't matter as long as you go from the first screw to the screw directly opposite of it and continue jumping across until all are tight.

    Pete DeBella also sells kits with diaphragms that are ethanol resistant.
     
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  14. May 17, 2022
    Oldpappy

    Oldpappy A.C. Fults - Curmudgeon at large 2022 Sponsor 2021 Sponsor

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    The replacement pumps a lot of suppliers sell are imports that will not last long. These can be spotted by looking at the glass bowl, if it appears to have a horizontal divider I would not buy it. I put one of those on one of my Jeeps and within a few months it began to leak around the bowl gasket no matter how tight the bail was. I put in a new gasket, and six months later the diaphragm was shot. I do not use ethanol gasoline in my Jeeps so don't know if it would have failed sooner with that.

    After that I rebuilt one of the old AC pumps I had in my shed, and that will be what I do going forward.
     
  15. May 17, 2022
    Eric

    Eric Member

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    Thank you for such a thorough list of ideas. Most of those have been dealt with correctly thanks to the advice of others here on the forum, but you introduce a few more. I might copy and paste your list and print it for my hard copy manual.
     
  16. May 17, 2022
    Eric

    Eric Member

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    The one in question does not have the valves held in place by a retainer... did AC ever produce them like this? Scoutpilot gave me a new avenue to research (Airtex or Kem) so I will look into that. Thanks as always.
     
  17. May 17, 2022
    scoutpilot

    scoutpilot Member

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    The history of AC pumps gets a little hazy during the late 50's and early 60's. It is likely that either Airtex or KEM were the perpetrators of the press-in valves because they cost less. As well, at about this time "planned obsolescence" was taking hold in American manufacturing.
     
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  18. May 17, 2022
    Glenn

    Glenn Kinda grumpy old man Staff Member

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    [​IMG]
     
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  19. May 17, 2022
    Glenn

    Glenn Kinda grumpy old man Staff Member

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    The above fuel pump was brand new. All I did was tighten the fitting and that section literally fell off. That's one of the ones with the glass with the center divider. I don't remember where I got it from.
     
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  20. May 17, 2022
    Oldpappy

    Oldpappy A.C. Fults - Curmudgeon at large 2022 Sponsor 2021 Sponsor

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    Yep, that is what I was talking about though I said "horizontal divider", the one I had that failed was exactly like the one Glen posted. I should have said "Vertical", but the bubble in my level isn't right some days.

    Those things are junk.
     
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