1. Welcome to Jeeps.net!

    You are currently viewing as a guest! To get full-access, you need to register for a FREE account.

    As a registered member, you’ll be able to:
    • Participate in all Jeep discussion topics
    • Transfer over your build thread from a different forum to this one
    • Communicate privately with other Jeep owners from around the world
    • Post your own photos in our Members Gallery
    • Access all special features of the site

Fuel delivery issue

Discussion in 'Performance & Tuning' started by r.a.johnson56, Jun 17, 2019.

  1. Jun 17, 2019 at 8:01 PM
    #1
    r.a.johnson56

    r.a.johnson56 [OP] Member

    Joined:
    Jun 17, 2019
    Member:
    #3381
    Messages:
    5
    Gender:
    Male
    Vehicle:
    1982 CJ-7 Jamboree
    Please help!

    My 1982 CJ-7 is not pushing fuel upstream of the mechanical fuel pump. Initially I was not sure what was happening so I rebuilt the carb and replaced the filter. After I discovered no fuel was pumping (by disconnecting the line prior to the carb), I replaced the sending unit/fuel pickup and the pump. Still with no success, I replaced all rubber lines.

    With all new rubber lines, I fed the line at the tank directly into a red fuel container to rule out the sending unit. All was good (fuel pumped). So I hooked the rubber line (with excess length) back to the actual fuel tank. All was good! So I cut the line to length and attached it with hose clamps thinking I had solved the issue. Turned her over... same problem... no fuel pumping!

    I am at a loss. I have intermittent fuel pumping and I can’t track down what causes it to work sometimes and not others. Literally everything is new except for the steel line. I have sprayed carb cleaner into the steel line, blown air through it, and don’t see a leak anywhere.

    Any ideas?
     
  2. Jun 18, 2019 at 5:38 AM
    #2
    chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine Moderator

    Joined:
    Jul 19, 2016
    Member:
    #2
    Messages:
    4,068
    Gender:
    Male
    Welcome to the site. I cant offer any advice, but someone should post up soon.
     
  3. Jun 18, 2019 at 6:00 AM
    #3
    Awrench

    Awrench Well-Known Member

    Joined:
    May 12, 2018
    Member:
    #2303
    Messages:
    975
    Gender:
    Male
    Vehicle:
    3 jeeps
    I am confused -:confused:
    thiss is a 1982 cj - with elec fuel pump in tank and carburetor?

    OR just the mechanical one on engine?
     
  4. Jun 18, 2019 at 6:15 AM
    #4
    Awrench

    Awrench Well-Known Member

    Joined:
    May 12, 2018
    Member:
    #2303
    Messages:
    975
    Gender:
    Male
    Vehicle:
    3 jeeps
    Any repairs to engine?
    removed Cam - ?
    Could the new fuel pump be -
    wrong pump?
    installed with arm not correctly on cam?


    Just got morning coffee - starting to think somewhat strait er....
     

    Attached Files:

  5. Jun 18, 2019 at 9:16 AM
    #5
    r.a.johnson56

    r.a.johnson56 [OP] Member

    Joined:
    Jun 17, 2019
    Member:
    #3381
    Messages:
    5
    Gender:
    Male
    Vehicle:
    1982 CJ-7 Jamboree
    Thanks everyone. It is a mechanical pump... the pickup in the tank is just the strainer and float.

    The motor is stock, no cam/crank changes. Pump was from Autozone, and is the same as the old one... fit perfectly and I compressed the lever when installing.
     
  6. Jun 18, 2019 at 12:04 PM
    #6
    TJ_abuser

    TJ_abuser Well-Known Member

    Joined:
    Sep 18, 2018
    Member:
    #2590
    Messages:
    1,013
    First Name:
    Todd
    Vehicle:
    2005 jeep unlimited
    2 inch lift, bumper and winch 33" mud claw
    Fuel filter?
     
  7. Jun 18, 2019 at 1:06 PM
    #7
    aggrex

    aggrex Well-Known Member

    Joined:
    Sep 12, 2016
    Member:
    #203
    Messages:
    4,831
    DE
    Vehicle:
    Backcountry '16
    Tuffy>AEV>TTO>JW>STech>EVOcage>MagnaFlow>SpiderTrax>RockHard>TF>SpringTail>67design>Bolt>GPCA>Curt>
    Autozone fuel pump is suspect having problems under pressure.
     
  8. Jun 18, 2019 at 2:48 PM
    #8
    Jim Beam

    Jim Beam Well-Known Member

    Joined:
    Feb 11, 2019
    Member:
    #2891
    Messages:
    596
    Gender:
    Male
    First Name:
    Donald
    Vehicle:
    1986 CJ7
    Fuel Injection, Dana 44s, T18, 4.10s w/lockers
    There is a length of 5/16" rubber fuel line that attaches from the end of the main fuel line to the tank. If this line is cracked from age or kinked it will not deliver fuel. I read where you stated that you did replace all the fuel lines but to do this would require dropping the tank. Some times when guys replace all the soft lines there is air in the lines that can cause an issue. If you open the fuel filler cap and disconnect the fuel line from the pump inlet, you could suck or use a hand pump fuel up to the pump inlet. Actually, it should create a siphon and fuel will begin to run out. Doing that will provide fuel to the pump. Another issue that can be a problem is poor ventilation in the fuel tank, this can prevent fuel from reaching the pump. Your CJ came with an excellent vent system consisting of a check valve, rollover valve, charcoal cannister, and related vent and fuel lines connecting it all together. A repair manual will lay this system out in detail. Also a good test for this system is done by removing the fuel filler cap after a drive and you should not be able to hear air rushing in as this would indicate a vent problem.
     
    aggrex and chris4x4 like this.
  9. Jun 18, 2019 at 2:49 PM
    #9
    r.a.johnson56

    r.a.johnson56 [OP] Member

    Joined:
    Jun 17, 2019
    Member:
    #3381
    Messages:
    5
    Gender:
    Male
    Vehicle:
    1982 CJ-7 Jamboree
    Possibly, but I had the same symptoms with the previous pump that was only a couple of years old.
     
  10. Jun 18, 2019 at 2:54 PM
    #10
    r.a.johnson56

    r.a.johnson56 [OP] Member

    Joined:
    Jun 17, 2019
    Member:
    #3381
    Messages:
    5
    Gender:
    Male
    Vehicle:
    1982 CJ-7 Jamboree
    Thanks Jim. The tank is currently dropped (to change the rubber line, pickup, and vent valves). I will see if I can siphon gas to the pump inlet (push the air out) and try turning her over again.
     
  11. Jun 18, 2019 at 2:59 PM
    #11
    Jim Beam

    Jim Beam Well-Known Member

    Joined:
    Feb 11, 2019
    Member:
    #2891
    Messages:
    596
    Gender:
    Male
    First Name:
    Donald
    Vehicle:
    1986 CJ7
    Fuel Injection, Dana 44s, T18, 4.10s w/lockers
    Another thing that can cause an issue is when the float bowl vent in the oem carb is stuck open after it sits awhile. This can dry out all the fuel in the float bowl and you have to crank the starter until the bowl fills up again. Pouring a bit of fuel down the carb throat can help until that bowl fills up. When you manually pump the throttle by hand and look down into the carb there will be raw gas squirting out from the accelerator pump nozzles, this will indicate fuel in the bowl. I had this issue and installed an electric pump just to fill up the bowl, shutting it off when full.
     
    aggrex and chris4x4 like this.
  12. Jun 18, 2019 at 3:43 PM
    #12
    Awrench

    Awrench Well-Known Member

    Joined:
    May 12, 2018
    Member:
    #2303
    Messages:
    975
    Gender:
    Male
    Vehicle:
    3 jeeps
    Am I confused - OP confirmed fuel to pump, new lines did a temp bypass and no pump output?
    But you know me its vacation time this week :drunk: bourbon sampling -
     
    TJ_abuser likes this.
  13. Jun 19, 2019 at 8:06 PM
    #13
    r.a.johnson56

    r.a.johnson56 [OP] Member

    Joined:
    Jun 17, 2019
    Member:
    #3381
    Messages:
    5
    Gender:
    Male
    Vehicle:
    1982 CJ-7 Jamboree
    Oh man, I think I figured it out. So, turns out my Jamboree has a 20 gallon tank. The sending unit was for the more common 15 gallon tank. I put 5 gallons of gas in the tank after cleaning it out. So it worked temporarily until the fuel ran down just enough.

    The old sending unit was so deteriorated I couldnt tell they were different lengths. man, what a relief to find a logical cause. The correct sending unit is being shipped!

    Thanks everyone for the help! All of the brainstorming helped lead me to the answer.
     
    aggrex likes this.
  14. Jun 20, 2019 at 6:19 AM
    #14
    Awrench

    Awrench Well-Known Member

    Joined:
    May 12, 2018
    Member:
    #2303
    Messages:
    975
    Gender:
    Male
    Vehicle:
    3 jeeps
    who said restoration was easy?

    Let me get my knife in - I always find these fault with big online pick your own part suppliers, parts selection is a job you want a knowledgeable pro helping . now back to coffee.
     
  15. Jun 20, 2019 at 3:01 PM
    #15
    Jim Beam

    Jim Beam Well-Known Member

    Joined:
    Feb 11, 2019
    Member:
    #2891
    Messages:
    596
    Gender:
    Male
    First Name:
    Donald
    Vehicle:
    1986 CJ7
    Fuel Injection, Dana 44s, T18, 4.10s w/lockers
    Since you are installing a new sending unit please allow me to offer some advice. The oem sending unit is grounded to the frame which is a poor electrical conductor of electricity and the ground has a long way to travel before it reaches the negative battery terminal. My suggestion would be to run a wire into the rear cable harness and attach one end to the battery negative and the other to the sending unit ground wire. Also add ground wires to the taillight housings and connect those to that ground wire from the battery. You should notice a brighter taillight and you can add some 50 watt taillight bulbs. Those filters that come with the aftermarket send units can clog up in time preventing fuel flow, which is what happened to me. There is an aftermarket stainless steel fuel pick up sock available or there used to be from the big box 4wd outfits.
     
To Top