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Bad sounding noise, fuel pump related

Discussion in 'Intermediate CJ-5/6/7/8' started by fesser, Oct 5, 2015.

  1. Oct 5, 2015
    fesser

    fesser Napa, CA 2024 Sponsor 2022 Sponsor

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    Disclaimer: My 75 CJ6 is the first AMC V8 powered vehcicle (304)I have ever owned.

    I am working toward making the Jeep driveable. The fuel pump was a leaky mess so I decided to attack that today. When I pulled the old pump off I am sure I heard something metallic fall inside the engine. I do have crappy old ears, and the stereo was on, but the "uh oh" alarm in my brain went off and said "what the eff was that"?

    Being familiar with Chevy's I looked and expected to see the push rod for the pump had bottomed out. Alas, no push rod on these engines. Did a quick search on here and am wondering if the drive gear for the distributor could have dropped off. Any ideas? What should I be looking for?

    Second Disclaimer: I do own the factory service manual but am less than impressed by it.

    Thanks. Frank
     
  2. Oct 5, 2015
    chosen1608

    chosen1608 Member

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    Not sure what you heard. The fuel pump runs off an arm which sits on a gear (eccentric) off the end of the cam shaft. Is the arm intact? Maybe part of that broke off. Sounds stupid, but you didn't accidentally drop a bolt in there? Good luck.
     
  3. Oct 6, 2015
    fesser

    fesser Napa, CA 2024 Sponsor 2022 Sponsor

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    Had both pump bolts off and on the bench. The pump was still in place held on by gasket sealer. Grabbed the pump and pulled it off the block and heard what sounded like something falling down inside the front of the engine. The arm on the pump looks fine. Maybe I am losing it but I swear I heard something.
     
  4. Oct 6, 2015
    PeteL

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

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    Not familiar with the 304, but IIRC some fuel pump arms have a contact plate or foot on the cam end. Is it possible something like that came loose?

    I think another member posted recently about finding such a mystery-piece in their oil pan.


    Tried a magnet to fish in the pan?
     
  5. Oct 6, 2015
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    There is an eccentric on the front of the cam gear that moves the fuel pump. There's a good picture of it in this thread - http://theamcforum.com/forum/no-spark-at-a-loss_topic23954.html

    It seems unlikely that the gear or eccentric has fallen off in service. There's nothing 'normal' that will fall off, unless you dropped a bolt into the timing cover or such. You should be able to see into the hole in the timing cover for the fuel pump. Get a bright light and use a mirror if needed. Test the slack in your timing chain. Now would be a good time to install a timing set, if the chain is loose.

    The FSM is meant for the line mechanics at the dealerships, so it assumes a fairly high level of understanding and experience. You can see the camshaft and eccentric in a drawint in the '82 manual here http://oljeep.com/edge_parts_man.html - fig 1B-112 - the engine internals do not change. The FSM seems to get more detailed as the years go by. There is also plenty of information online if you search with the right terms.
     
  6. Oct 6, 2015
    Walt Couch

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

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    I suspect the pump was on the power stroke and when you pulled it out the pump arm slammed home making that clunk sound. I hope this is what happened. If you think the dist gear has fallen off then rotate the rotor. If you can freely rotate the dist shaft then the gear is gone.
     
  7. Oct 6, 2015
    fesser

    fesser Napa, CA 2024 Sponsor 2022 Sponsor

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    Thanks gentlemen. I will give it a more thorough inspection in a couple of hours. Timing chain is good advice but I just want to get it to run and idle first to make certain that she is "a runner". We drove it with a gas can plumbed to the carb for a minute or two when we first got her home but it has been awhile. If she runs I plan to strip off what I can to clean and paint the engine. If I get to that it will get new timing chain, water pump, thermostat, etc.
     
  8. Oct 6, 2015
    fesser

    fesser Napa, CA 2024 Sponsor 2022 Sponsor

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  9. Oct 6, 2015
    zila

    zila I throw poop

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    Sounds to me like the rattling noise you heard has some merit.. Me? I'd drop the pan and see if anything is in there, then check in the timing cover.. .. Or ditch the mechanical pump and install an electric one. In my 75 I moved mine to the fuel tank.
     
    Last edited: Oct 6, 2015
  10. Oct 7, 2015
    fesser

    fesser Napa, CA 2024 Sponsor 2022 Sponsor

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    So in doing more searches I see that making sure the arm is on the correct side of the eccentric is frequently mentioned. Dumb question, is it even possible to install the pump with the arm on the wrong side of the eccentric?
     
  11. Oct 7, 2015
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    I would not think so, though I have not tried. I wouldn't think you could install the bolts if the arm were on the wrong side.

    There is a fuel pump type for these engines with the connections pointing up, and one that points down. The arm rides on the top or bottom of the eccentric, depending on which type. Maybe that's what they are referring to?
     
    Last edited: Oct 7, 2015
  12. Oct 7, 2015
    Walt Couch

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

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    It's easy to tell which one you have (pump). Holding the pump in it's mounting position, if you have to push down on the pump lever then this type mounts under the eccentric. So it will be the opposite for the over top eccentric.
     
  13. Oct 7, 2015
    fesser

    fesser Napa, CA 2024 Sponsor 2022 Sponsor

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    I am going to give it another go later this afternoon. Mine is the type that pushes down. It was identical to the one I took out. Seemed like it went in properly as I had to pull up on the pump body in order to start the bolts which would make sense if the arm was under the eccentric. I almost miss getting angry at Chevy fuel pumps when the little pushrod would fall all the way down. Dealing with engines I am not familiar with makes me feel a little stupid. Thanks again gentlemen.
     
    Last edited: Oct 7, 2015
  14. Oct 7, 2015
    fesser

    fesser Napa, CA 2024 Sponsor 2022 Sponsor

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    I like to read updates when following other threads, so here is the latest on my problem. I will try to keep it short. First, the pump was put in correctly (arm under eccentric). Second, even though I had put in a new tank, I wasn't smart enough to flush the lines before putting in a new pump. I flushed the main line by putting compressed air into the fuel tank (with new fuel in it) and running the line that should go into the fuel filter into a hose that fed into a container. For those of you that are smarter than me, you already know that what I did was force any crud that was in the line between the tank and the pump into and through the pump. After removing checking and reinstalling the pump, it became obvious that it wasn't pushing (or pulling?) fuel. Took the new pump off and peeled back the crimp that holds it together. Found lots of little rust rocks that kept the little diaphrams from doing their jobs. Tomorrow I intend to flush the line again, add a filter before the pump, and install a new pump. I am pretty sure I have found my fuel supply problem.
     
  15. Oct 7, 2015
    zila

    zila I throw poop

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    I had the same problem on my 75 when I bought it.. Crud in the tank.. Mine ran but uphills made it labor and die. After a month of trying everything I could think of, I decided to replace the sock in the tank pickup.. I siphoned as much fuel out as I could by removing the filler hose. I used a clear hose. There was a bunch of nasty looking stuff that came through the hose. After dropping the tank I removed the fuel line and return at both ends,. Blew compressed air through both. Cleaned the tank, re-installed everything, new fuel and life was good again.
     
  16. Oct 24, 2015
    fesser

    fesser Napa, CA 2024 Sponsor 2022 Sponsor

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    Delayed update, put in a new pump (that wasn't full of rust and crud) and she ran fine.
     
  17. Oct 24, 2015
    PeteL

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

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    Good to know!
     
  18. Oct 25, 2015
    Walt Couch

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    Glad you are back on the road.
     
  19. Nov 8, 2015
    PeteL

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

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    Here is a thread with a pic of the part I was describing in post #4 above. Maybe that ws the noise you heard?
     
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