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Thread: Any one familiar with older vehicles with mechanical fuel pump

  1. #1
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    Any one familiar with older vehicles with mechanical fuel pump

    1970 CJ sort of with V-6 keeps eating fuel pumps. Last about 2 total hours of run time. Vehicle has two tanks with electric switching valve. Never been right since I took it to a shop to have valve replaced. The hose's look right but????? Any ideas?

  2. #2
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    Re: Any one familiar with older vehicles with mechanical fuel pump

    Ok, I'll ask some questions. What do you mean eating them? A mechanical fuel pump is a pretty simple and straightforward device. It has an arm that is pressed on by a lobe on the camshaft. That arm presses in on a diaphragm which pushes the fuel out the discharge and when the lobe rolls off the arm a spring pushes the diaphragm the other way which sucks on the fuel suction line pulling new fuel into the pump. Is the arm bending, is the diaphragm breaking or getting a pinhole leak or is the housing cracking. You can also get an in-line electric fuel pump (make sure it's not a high pressure one designed for fuel injections systems) and a plate to block off the opening left by removing the mechanical pump. I would try putting a fuel filter inline after the tank valve and before the pump. I recommend the old glass ones so you can see what is going on assuming you can get it mounted high enough to see it easily.
    90 YJ, 93 4.0l, AX-15, 3.55 D35/30 with ARB F/R, Atlas 4.3:1, Warn Full Float kit rear, on 33's, M.O.R.E motor mounts, 1" BL, Warn 9k.

  3. #3
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    Re: Any one familiar with older vehicles with mechanical fuel pump

    Also, the CJ's didn't come with a V6. They had a straight six. Can you verify which engine is in the Jeep? Pictures? Are you buying the right fuel pump for it?
    82 Cherokee WT SOA/SF/high steer/Alcan springs/agr box/Borgeson steering shaft/AMC 401/performer/holley TA/HEI/BeCool/727/ALTAS (2.0/2.72/5.44)/D60 Snofighter(Yukon Zip,hubs,stubs,4.56)/14 Bolt (FF,BF shave, Discs, ARB,Artec Truss)/MTR 37X12.5/Corbeau Moab Seats/RCI 6point Harness/Hella Aux lights/tuffy console/killer32 sliders/custom bumpers and roll bar/WARN 8000/steering brace/CO2 Tank/CB/dual batts/custom TC skid plate

  4. #4

    Any one familiar with older vehicles with mechanical fuel pump

    Quote Originally Posted by Will E View Post
    Also, the CJ's didn't come with a V6.

    Not true. The vast majority of CJ5s came with the Dauntless 225... CJ6s came with them as well... just saying.

    Edit: The Dauntless was retired from production in 1971. So, his 1970 could easily have one or a replacement GM 231 in it.
    Last edited by Huck; 07-30-2018 at 08:26 AM.
    yah, Huck you newbie, Rubicon drivin', mall Cruisin', bling-bling, bolt-on, got no drivin skillz, drove thru a AutoZone with a crap magnet attached, H2 wannabe, poseur! Pay attention!
    If you would pry your sorry arse out the Scottsdale Fashion Square once in a while you would know more about the BLM and the USFS (you do know those acronyms, right?).

  5. #5
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    Re: Any one familiar with older vehicles with mechanical fuel pump

    Quote Originally Posted by Huck View Post
    Not true. The vast majority of CJ5’s came with the Dauntless 225... CJ6’s came with them as well... just saying.

    Edit: The Dauntless was retired from production in 1971. So, his 1970 could easily have one or a replacement GM 231 in it.
    Well ya learn something new every day! I do not ever recall seeing a V6 in a CJ, but most of the time I am not looking either.
    82 Cherokee WT SOA/SF/high steer/Alcan springs/agr box/Borgeson steering shaft/AMC 401/performer/holley TA/HEI/BeCool/727/ALTAS (2.0/2.72/5.44)/D60 Snofighter(Yukon Zip,hubs,stubs,4.56)/14 Bolt (FF,BF shave, Discs, ARB,Artec Truss)/MTR 37X12.5/Corbeau Moab Seats/RCI 6point Harness/Hella Aux lights/tuffy console/killer32 sliders/custom bumpers and roll bar/WARN 8000/steering brace/CO2 Tank/CB/dual batts/custom TC skid plate

  6. #6
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    Re: Any one familiar with older vehicles with mechanical fuel pump

    I used to run a CJ-5 in the 70's, and it had a Buick V-6 225, factory from what I understand.
    Did not have much more power than a 4 cyl though.

  7. #7
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    Re: Any one familiar with older vehicles with mechanical fuel pump

    Make sure the return line to the tank is not plugged.
    Non-College Educated Working Class White Deplorable....

  8. #8
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    Re: Any one familiar with older vehicles with mechanical fuel pump

    Never mind, mis-spoke
    37's,locked,4.88's,6" lift,4:1tcase,winch,caged

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