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Fuel Problems

Discussion in 'Early CJ5 and CJ6 Tech' started by jwmckenzie, Jan 20, 2017.

  1. Jan 20, 2017
    jwmckenzie

    jwmckenzie Sponsor

    Boston, MA
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    Been chasing problems with my Dauntless for several months. Runs a bit and then just dies, like is out of gas. Started with electrical, new coil, condenser, etc, then moved to fuel, new fuel pump, cleaned all the lines out, installed the fuel return line. When it happens there is no fuel at the carb. But after it sets a while it will run. Sometimes for a short time, some times for a longer time.

    Went into the motor and am doing a complete rebuild, due to other issues.

    I found the fuel pump eccentric was installed backward, you can see the wear in the eccentric.

    [​IMG]

    I was hopeful I would find more of a clear root cause, like the eccentric broken, or turning on the cam. What are the chances this caused the problem?
     
  2. Jan 20, 2017
    william_cj3b

    william_cj3b 3BOB driver 2019 Sponsor

    Milton, FL
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    Are you sure you still have spark when it stops running? I've had a ballast resistor cause very similar behavior.

    Also, have you measured the output of your fuel pump? Any scale in the tank?
     
  3. Jan 20, 2017
    jwmckenzie

    jwmckenzie Sponsor

    Boston, MA
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    New ballast resistor, have spark. New fuel pump when tested is good, no scale in tank.
     
  4. Jan 20, 2017
    WorkInProgress

    WorkInProgress Member

    Kennewick, Wa
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    What about a fuel cap thats not venting properly? after it stops running on you, pull the cap and see if you hear or feel a vacuum on the gas tank.
     
  5. Jan 20, 2017
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    Does it happen only when driving or just any time? Do you have another fuel pump to compare it with? Years ago I bought a fuel pump that was supposed to be for an F-head. It would be fine when idling but when driving it couldn't pump enough fuel. Something about the arm was just a bit different.
     
  6. Jan 21, 2017
    Rick Whitson

    Rick Whitson Detroit Area 2020 Sponsor 2019 Sponsor

    I live South of...
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    Just something to consider, I was working on a Morgan three wheeler someone else had put in the motor. The carb kept overflowing gas, I checked everything could not find anything wrong. I was looking in the box of parts and noticed a spacer for the fuel pump, I pulled the fuel pump off, noticed it had a wear mark on the arm farther up the arm. I put the spacer on the fuel pump, that moved it out farther, shortened the stroke and problem solved. Does your fuel pump have a spacer on it? Just a thought, Good Luck.
     
  7. Jan 21, 2017
    jwmckenzie

    jwmckenzie Sponsor

    Boston, MA
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    Fuel cap - is venting OK. But put a new one on.

    Mostly happens when running but has happened at idle. It had an old fuel pump that ran I ran for the 1st 200 miles after I put it back together, when this started. Put a new pump from Walcks on and still the same issue.

    No spacer, will look at this as I go back together with the engine.

    I took a look at the wear on the fuel pump arm this morning. I can see two different wear points, one on the flat (where it should wear) longer one and one on the radius from the flat to the side of the arm, short one. Doesn't look like a full stroke of the pump??
    [​IMG]
     
    Last edited: Jan 21, 2017
  8. Jan 21, 2017
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    Definitely looks like a reduced stroke to me. You say it was ok for maybe 200 miles but then the problem started? Does the eccentric have a lobe or is it offset? Is it maybe inferior metal and it just wore out maybe?
     
  9. Jan 21, 2017
    jwmckenzie

    jwmckenzie Sponsor

    Boston, MA
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    It's offset. Pulled it off the camshaft to get a pic and you can see it is worn in an unusual manner due to being installed backward. You can see where the arm has "fallen off" the eccentric.

    [​IMG]

    Just as an editorial comment. With the "F" clearly marked, how can you NOT install it with the "F" facing forward... but someone did.
     
  10. Jan 21, 2017
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    Yeah, unbelievable but someone managed to. It would seem you definitely found the problem.
     
  11. Jan 21, 2017
    jwmckenzie

    jwmckenzie Sponsor

    Boston, MA
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    Hope so. Will know in a few weeks when I get it back on the road.
     
  12. Jan 21, 2017
    PeteL

    PeteL Member 2020 Sponsor 2019 Sponsor

    Hills of NH
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    Those dual marks on the pump arm make it look like the arm was bent (twisted), then the second mark was made.
     
    Glenn likes this.
  13. Jan 21, 2017
    PeteL

    PeteL Member 2020 Sponsor 2019 Sponsor

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    Hence the expression, "F-ed up."
     
  14. Jan 21, 2017
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    I agree. Started out ok, a little play developed and that was it. Started slipping off the edge.
     
  15. Jan 22, 2017
    jwmckenzie

    jwmckenzie Sponsor

    Boston, MA
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    Sorry for the slow drip on evidence, as I was looking how the arm might have gotten bent, no evidence of that, but it certainly has play side to side, but not excessive. Also with the new fuel pump, the Jeep behaved the same. The new pump has similar wear pattern on the edge of the arm as the old pump, I can see sometimes it got a full stroke, but mostly not. This is a pic of the wear on the eccentric that I think made the arm slip off the edge. I am now pretty confident this is the source of the problem. Thanks for the help.

    [​IMG]
     
  16. Jan 22, 2017
    Walt Couch

    Walt Couch sidehill Cordele, Ga. 2020 Sponsor 2019 Sponsor

    cordele, Ga.
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    The portion of the eccentric (where marked F) is designed that way to act as an oil slinger. You can easily see that the pump arm was running dry. No doubt in my mind that you have found your problem. Good catch on this problem.
     
  17. Jan 22, 2017
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    That eccentric looks like it's worn out. Are new ones readily obtainable?
     
  18. Jan 22, 2017
    jwmckenzie

    jwmckenzie Sponsor

    Boston, MA
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    Yes, $85. Some suggest it is the same as a 350, but didn't verify as my donor engine has a good eccentric, so once again my decision to buy that extra engine has paid off.

    "Even a blind pig will find an acorn."
     
  19. Jan 22, 2017
    compostwerks

    compostwerks Sponsor

    Canterbury, NH
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    I had an identical problem recently. There was something plugging up the outlet of the fuel tank. Very simply blew air through the line back to the tank.

    Next time it dies, look at your fuel filter to see if it's fuel starved.

    I think if it were the fuel pump, it would not be an intermittent problem.

    Pete
     
  20. Aug 5, 2020
    jwmckenzie

    jwmckenzie Sponsor

    Boston, MA
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    The Saga Continues: The jeep started acting like it was running out of gas ***AGAIN***, so dug back into the ignition system and fuel system. Here where I am at.

    The fuel system. When taking the Rochester 2G apart to look for blockage and proper function of the float and float valve, I found this likely very rare issue. The power valve has a washer that was able to go up and down the spring. When I took the air horn body off the carb the washer was hung between the power valve and the float. Here are some pics.

    [​IMG]
    [​IMG]
    [​IMG]

    Installed a new Power valve and a brass float.

    The ignition system. I decided to look at the ignition resistor and give it a visual inspection. I found a tail on the resistor that stuck out beyond the housing. It's far enough out that I could be shorting out on the firewall.

    [​IMG]

    Seems like I am in the rare and obscure problems with this 225.

    Test runs are good. Hope is not a plan, but I hope this fixes the issue.
     

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