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new fuel pump...bad?

Discussion in 'Early CJ5 and CJ6 Tech' started by WRMorrison, Aug 5, 2012.

  1. Aug 5, 2012
    WRMorrison

    WRMorrison Member

    Mesa, AZ
    Joined:
    Jul 28, 2012
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    217
    I'm doing my best to get this F-134 running this weekend...

    Everything's buttoned-up and going well, but the fuel pump (new; never installed) isn't pumping fuel...not even a little bit. I've taken the pump off and on several times to make sure I'm not doing some wrong (like not having the fuel pump lever on top of the cam lobe), but can't find anything wrong. Not an drop of fuel is making it to the pump. I've blown air through the fuel line and can hear it bubbling in the tank, so I know the line isn't clogged. I didn't purchase the pump (it came with the Jeep), but maybe it's not the right pump? It looks just like every other fuel pump for this vehicle that I've looked at (glass bowl on top; no vacuum ports, just inlet / outlet).

    It's driving me crazy because I'm so close I can taste it... It will fire up and run for a few seconds with a shot of starting fluid, so I know that once the fuel issue is solved that it will at least run. The only thing left that I can think of is maybe the camshaft is broken and not spinning?

    -WRM
     
  2. Aug 5, 2012
    piffey263

    piffey263 Active Member

    Medford, OR
    Joined:
    Oct 16, 2008
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    1,214
    i'm not sure why the fuel pump isn't working, but gas down the carb can keep engine running longer than starting fluid. (in my experience that is, my 65 chevy doesn't like starting if it sits for 3 months and fuel down the carb gets the engine running long enough for the mechanical pump to start pumping gas to the carb.)
     
    Last edited: Aug 5, 2012
  3. Aug 5, 2012
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
    Joined:
    Sep 23, 2002
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    12,529
    Unhook fuel line from tank at the pump, hook up vacuum pump, take reading. Should have good suction. If not, remove pump, operate by hand, check vacuum. If not its the pump. If decent vacuum then either installation problem or maybe a cam lobe issue.


    Sent from my iPhone using Tapatalk
     
  4. Aug 5, 2012
    WRMorrison

    WRMorrison Member

    Mesa, AZ
    Joined:
    Jul 28, 2012
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    I never thought of that; I'll try that next. I did hook up the vacuum pump to the fuel line (to make sure there were no obstructions) and it pulled fuel from the line with little to no effort, so I know there aren't any blockages. I'll hook it up to the pump here in a few minutes.

    -WRM
     
  5. Aug 5, 2012
    Stout

    Stout Member

    Quakertown, PA
    Joined:
    Nov 1, 2010
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    958
    How much gas do you have in the tank? I had a similar problem when trying to fire mine up for the first time in that I only put a gallon of gas in the tank and it wasn't enough to make it around the baffle. I disconnected the fuel line from the bottom of the tank and nothing came out. Adding another gallon fixed it.
     
  6. Aug 5, 2012
    WRMorrison

    WRMorrison Member

    Mesa, AZ
    Joined:
    Jul 28, 2012
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    217
    I just put 5 gallons in it, so, over half-full (or half-empty for you pessimists out there...lol).

    I just came in from the garage; had the vacuum gauge on the pump, and it's not creating any vacuum... So, I have a junk, new pump. :evil: I wasn't the original purchaser, and have no idea where it came from, so no way I can return or exchange it. Well, I guess I can buy the correct pump now with the vacuum ports for the wipers.

    -WRM
     
  7. Aug 5, 2012
    Mudweiserjeep

    Mudweiserjeep JEEP: Bouncy and Fun

    tipp city, ohio
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    Jun 17, 2004
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    Check you gas lines. If you have any holes (leaks) you will lose suction. I had an old truck with a rusty sending unit port. Rust hole was causing me all kinds of trouble.
     
    Last edited: Aug 5, 2012
  8. Aug 5, 2012
    PeteL

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

    Hills of NH
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    Might just be the gasket under the glass dome. They can be crooked, get dried out, shrink etc. Make sure the dome is tight, too.

    The other fixable possibility, other than a bad diaphragm, is a piece of crud in one of the two check valves.
     
  9. Aug 5, 2012
    1960willyscj5

    1960willyscj5 Well-Known Member

    Mesa, Arizona
    Joined:
    Nov 27, 2006
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    2,793
    Does the pump indicate in any way which way the fuel flows through it?
    I am on the crippled list and cannot just run out and check, but I seem to remember the fuel line coming from the tank and going into the FRONT port, then the fuel went from the REAR port to the carb.

    My mechanical is no longer operational, and I have installed an electronic MR Gasket pump in place of it.
     
  10. Aug 5, 2012
    WRMorrison

    WRMorrison Member

    Mesa, AZ
    Joined:
    Jul 28, 2012
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    Good idea; fuel line is cheap.

    While I don't know really know what all I'm looking at, I took the pump apart to see if there was anything obvious causing the problem, but everything looks good (to me).

    I don't remember there being the usual "flow arrow," but I can check tomorrow. It looks just like this pump (except mine has a filter screen near the bottom of the fuel bowl):
    [​IMG]

    Ports are on the left and right (looking at it mounted). I just assumed that the side facing the gas tank was the inlet and the other side was the outlet; this is how every other fuel pump is plumbed that I've seen in pictures. It looks as if fuel comes into the pump on the side with two circles in the bottom (some type of port/needle?), flows to the other side somehow, comes up through the filter screen (looks like brass) and finally goes back down through another port and out the outlet.

    -WRM
     
  11. Aug 5, 2012
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
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    Sep 23, 2002
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    I meant to say vacuum gauge but a vacuum pump with a gauge will work as well.


    Sent from my iPhone using Tapatalk
     
  12. Aug 9, 2012
    jeff1960cj5

    jeff1960cj5 New Member

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    Just had the same problem!!!!! Disconnect the fuel line at the carb, turn the motor over until gas shoots accross the garage! worked for me.
     
  13. Aug 9, 2012
    WRMorrison

    WRMorrison Member

    Mesa, AZ
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    Jul 28, 2012
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    I tried that...no-go. I attached a vacuum gauge to the tank side of the pump and turned the engine over; not pulling any vacuum.

    -WRM
     
  14. Aug 9, 2012
    WorkInProgress

    WorkInProgress Member

    Kennewick, Wa
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    Its already been mentioned, but i thought id mention that i recently replaced my metal style vacuum fuel pump with a glass bowl replacement from walcks and my inlet and outlet ports were on different sides of the pump, so i had to bend my lines to reach the opposite side of the pump they were on when i had the metal vacuum style pump. my new glass bowl did have tiny arrows on each port indicating which way fuel should flow. so now mine works fine with the tank side line on the front port thats towards the front of the vehicle and my line that leads to the carburetor is on the rear port thats on the side of the firewall.
     
  15. Aug 9, 2012
    WRMorrison

    WRMorrison Member

    Mesa, AZ
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    Jul 28, 2012
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    I suppose anything is possible; there's nothing embossed on the pump stating which direction the flow is supposed to go. Here's a pic of the pump with the glass bowl removed, maybe someone more familiar with the pump can recognize something out of the ordinary. This would be the top view as you're looking down and at the pump from the left side of the engine where it's mounted. The right/straight port is going to the tank and the left/90 degree port goes up and over to the carburetor.

    Does everything look to be on the correct side? Strainer side is on the carb side of the pump.

    -WRM

    [​IMG]
     
  16. Aug 9, 2012
    WRMorrison

    WRMorrison Member

    Mesa, AZ
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    Dang it...I just saw the arrows now, looking at the pic...LMAO!

    -WRM
     
  17. Aug 9, 2012
    WRMorrison

    WRMorrison Member

    Mesa, AZ
    Joined:
    Jul 28, 2012
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    Well, I re-installed the pump and swapped the hoses around, but it still doesn't appear to be pumping fuel yet. I put the vacuum gauge back on it (on the correct side of the pump, now) and it is pulling...slight, but it's working. Is there a good way to prime the pump other than by draining my battery?

    -WRM
     
  18. Aug 10, 2012
    PeteL

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

    Hills of NH
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    Apply vacuum to the output side.
     
  19. Aug 10, 2012
    WRMorrison

    WRMorrison Member

    Mesa, AZ
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    I'll do that tonight; thanks.

    Another question; is there any reason why I can't unscrew the two halves of the pump and turn the top half 180 degrees? This would put the flow in the right direction, and my lines wouldn't be routed weird.

    Also, a co-worker of mine mentioned (after seeing the pics) that he thought the spring-loaded check valves (in the right half of the fuel bowl in the picture) should be on the tank side of the fuel pump. Is this correct? He seems to think that the valves were put in on the wrong side of the pump.

    -WRM
     
  20. Aug 10, 2012
    WorkInProgress

    WorkInProgress Member

    Kennewick, Wa
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    i heard if you pull out the choke a little bit while cranking it will help prime the pump. and its probably a good idea to replace the fuel filter if you have one in-line. shortly after i replaced my fuel pump with the glass bowl i started having issues acting like vapor lock although i had one of those fancy take apart clean and re-use hot rod style filters it was recently cleaned and i couldnt hardly blow through it. so i just replaced it with a wix plastic filter thats see through and all my problems went away.
     
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