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Fuel Issue Help

Discussion in 'Intermediate CJ-5/6/7/8' started by Tree cutter 08, Apr 26, 2020.

  1. Apr 26, 2020
    Tree cutter 08

    Tree cutter 08 Member

    Cleveland ga
    Joined:
    Feb 14, 2019
    Messages:
    111
    This is actually a 80 cj5 but basically the same as the intermediate as far as the fuel system. Some experts here so here it goes. Just installed rebuilt 360. Attempted to do the break in procedure today. Filled the fuel bowl and fired it off. Went dead quickly. Tried again and same thing. After winding over several times I quit in fear of wiping a cam lobe. Checked fuel lines and they were dry. Took line off at the pump and blew back into the tank. I quit and fuel instantly started running out so I hooked it back up and tried it again. Same thing. Took pump off and manually pumped it and it shoots fuel like crazy. Line from pump to filter and carb is clean. Reckon the arm is bent and not enough movement to make it pump? Everything is new. Only thing I haven't tried and don't know if I can with limited space is to hook line back up to the carb and manually pump it to the carb then install it back on the block.
     
  2. Apr 26, 2020
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Hills of NH
    Joined:
    Aug 3, 2003
    Messages:
    9,754
    Tried it with the gas cap loose? Maybe an issue with fuel tank vapor recovery system or whatever they had in '80?
     
  3. Apr 27, 2020
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
    Joined:
    Aug 10, 2003
    Messages:
    23,596
    This forum also covers "late" Jeeps, '76 on.

    Your '80 TSM has a diagram of the vapor recovery system. The tank must be vented through the vapor recovery canister (charcoal canister) to prevent fuel starvation due to vacuum building up in the tank above the fuel.

    More Information for DETROIT IRON DCDC112

    The TSM also has a pressure spec for the fuel pump that you can measure using a gauge. Amazon sells inexpensive vacuum / fuel pump pressure testers that will work fine. There's no spec, but you can look at how much fuel the pump delivers by cranking the engine and directing the fuel into a jar. Obvious safety precautions here - don't start a fire and don't let the engine start and run you over.

    Assuming youhave a carburetor and not EFI, the engine will run with a gas can on the cowl, feeding by siphon. You don't need much fuel pressure.

    NoFuelPump.jpg
     
    Last edited: Apr 27, 2020
  4. Apr 27, 2020
    jpflat2a

    jpflat2a what's that noise?

    Hermosa, SD
    Joined:
    Jul 30, 2003
    Messages:
    8,513
    Are you sure you have the pump arm installed properly over the eccentric ?
    Was the eccentric even installed ?
     
  5. Apr 27, 2020
    Tree cutter 08

    Tree cutter 08 Member

    Cleveland ga
    Joined:
    Feb 14, 2019
    Messages:
    111
    Thanks for the advise guys, got it running. I hooked lines up and manually pumped it until it filled the fuel bowl. Then installed pump and did a 30 min break in run time. Engine seems to run good but can't get a good idle. Runs great if idle is set at 1000 to 1100. Runs great and smooth above that. Going to hunt vacuum leaks tommrow.
     
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