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fuel pump saga

Discussion in 'Early CJ5 and CJ6 Tech' started by chuckdiesel, Nov 5, 2014.

  1. chuckdiesel

    chuckdiesel New Member

    About a year ago i completed my 1960 cj f134 engine rebuild. I tried the mechanical fuel pump i purchased from KW with the really cool glass dome on top but it never seemed to send enough fuel to the engine. I tried another fuel pump with the same result and came to the assumption that the pumps may not have been getting enough action from the (new) cam. I decided to try an electric pump. I have replaced the electric pump (low volume) now four times in twelve months and incidentally they choose really inappropriate time to decide to quit. To my best understanding the pumps are "pushers, not pullers" and should be positioned as close to the tank as possible. This situation is difficult to overcome because the tank is under the seat and is a very short distance to the carb where ever it is placed. The parts guys have been very good about replacing the pumps for free but my conscience is starting to suggest a long term solution. I would really like to use the original type glass dome type pump and would really appreciate anyone weighing in with their expertise with this problem.
    Thanks in advance
     
  2. Howard Eisenhauer

    Howard Eisenhauer Administrator Staff Member

    What are the symptoms that make you suspect there's not enough fuel getting through?

    What make/model carb are you using?

    Have you checked that the fuel line / tank pickup is clear?

    Are you seeing bubbles coming up into in the glass bowl of the mechanical pump while the engine is running?

    Is the glass bowl full of fuel or only up the the level of the filter screen?

    H.
     
  3. chuckdiesel

    chuckdiesel New Member

    1. Engine would sputter and refuse to rev up but with electric runs great
    2.new tank and line
    3.small trickle at the bottom. I never saw the gas touch the bottom of the glass and don't remember any air bubbles.

    Thank you
     
  4. Walt Couch

    Walt Couch sidehill Cordele, Ga. 2024 Sponsor 2023 Sponsor 2022 Sponsor

    You say "new tank" so is it plastic or metal? If it's Omix-ada plastic then be advised they had problems with plastic shavings inside tank that would plug the bottom fuel line out. If you unscrew the line going into the bottom of the tank you should get a strong stream of fuel out.
     
  5. chuckdiesel

    chuckdiesel New Member

    It's a new metal tank.
    Thanks
     
  6. Howard Eisenhauer

    Howard Eisenhauer Administrator Staff Member

    Sorry, I don't follow here. The fuel in the glass has to come up at least to the filter screen, that's where it enters into the pump output channel & then to the line going up to the carb.

    H.
     
  7. chuckdiesel

    chuckdiesel New Member

    Is it reasonable that the fuel only stays in the bottom of the pump and never reaches the level of the bottom of the glass dome? Thanks
     
  8. oldtime

    oldtime oldtime

    No that makes no sense.

    What year and model is your CJ ?
    Please identify the fuel pump brand and model.

    The gasoline supplied to the carburetor must be sufficient or else the carburetor cannot properly mix the fuel.

    Sufficient amount of gasoline must exit the tank.
    You will need to verify that the pickup tube is not plugged with debris via reverse air purging and the tank cap must be vented.

    The gasoline must reach the fuel pump.
    Reverse purge the supply tube with air pressure.
    Make sure fuel pump is not sucking in air from loose supply tube fittings.
    You will need to verify via fuel level inside the inverted glass dome.

    The gasoline must reach the carburetor.
    You will need to verify that if you have a gasoline filter at the carburetor inlet.

    The gasoline level in the carburetors fuel well must be at correct level.
    First you will need to verify your carburetor model.
     
  9. chuckdiesel

    chuckdiesel New Member

    Is it reasonable that the fuel only stays in the bottom of the pump and never reaches the level of the bottom of the glass dome? Thanks
     
  10. oldtime

    oldtime oldtime

    Either the pump is not sucking or the gasoline supply is restricted somewhere between the tank cap and the inlet to the fuel pump.

    Disconnect fuel tube at fuel pump.
    Remove tank cap.
    Reverse air purge the supply tube with pressure.
    Listen at tank opening for debris being dislodged from the supply tube or tank pickup.
    Reconnect supply tubing and make sure that all fittings are air tight.
     
    Last edited: Nov 5, 2014
  11. Howard Eisenhauer

    Howard Eisenhauer Administrator Staff Member

    As Ken said no it's not. The fuel comes into the pump, is forced into the glass bowl by the action of the diaphragm & check valves, fills the bowl until it reaches the level of the filter screen & then is forced (by the pressure of more fuel coming in ) through the screen & out through a passage in the pump body into the fuel line going to the carb.

    In actual practice the fuel level should be above the level of the screen as the remaining air in the bowl tends to get forced out to the carb as the jeep bounces around.

    Have you tried disconnecting the fuel line at the carb & seeing if the pump will put something out into a container while cranking the engine? (You might want to try this with the pump drawing from a jug of water rater than gas, water being less libel to go 'boom" :( )

    H.
     
  12. chuckdiesel

    chuckdiesel New Member

    This is a lot of great info and I appreciate the help. Is there anyone who has an electric pump that has been reliable? If so what kind is it ? It will be a few days before I can work on this and I will report my trials! Thanks
     
  13. tcfeet

    tcfeet Member

    I have one on my 64 F134. Was on it when I bought it four years ago. Never had a bit
    of problem with it. I have not a clue what brand or model it is..Its mounted to the frame rail
    on the left side, near the under seat tank...
     
  14. hewebb

    hewebb New Member

    I installed a Mr. Gasket 42S electric fuel pump. I mounted it in the frame under the tank location. Works well. Make sure you have a vented gas cap. I removed the manual pump and placed a cover over the location. Engine is Hurricane 4 cyl. I kept having issues with debris in the system. I removed the tank and found that the person that rebuilt/replaced the tank got paint in the neck that was flaking off into the tank.
     
  15. 1960willyscj5

    1960willyscj5 Well-Known Member

    I have the Mr. Gasket electric also. Been on there about 5 years now. Just remember to place the inlet side of the pump lower than the bottom of the gas tank. That is why a lot of guys place the electric pumps inside the frame rails just forward of the gas tank.

    I also use two replaceable fuel filters, one before the pump, and one between the pump and the carb.
     
  16. scoutpilot

    scoutpilot Member

    Just remember...battery dies, fuel pump dies, electronic ignition dies. Push start now out of the equation. OH, yeah and for the conspiracy theorists out there, EMP? Your screwed.
     
  17. PeteL

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

    Good points.
     
  18. blevisay

    blevisay Oh Noooooooooooooooo! Staff Member

    are there any spacers between the block and the pump?
     
  19. 1960willyscj5

    1960willyscj5 Well-Known Member

    If it isn't running at the time, EMP won't have any effect on it.

    And roll starting it depends on if you have a generator or an alternator.
     
    Last edited: Nov 8, 2014
  20. Alan28

    Alan28 Well-Known Member 2022 Sponsor

    Just to say that it will work one day. I have a F134 with manual fuel pump (you action the pump by end to fill the carb, then it works non stop) and it was useful to check all from the tank to find problems. At last it worked perfectly. So... take time to check and re-check. One day happiness will come.
    :iagree: WITH MYSELF.