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Cj5 258 6 Just Stops Running

Discussion in 'Intermediate CJ-5 and CJ-6 Tech' started by David329, Aug 3, 2018.

  1. Aug 3, 2018
    David329

    David329 New Member

    Va
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    Have replaced carb coil gas tank sending unit doesn't seem to be over heating it's not boiling or hissing put a laser temp gun on it never went pass 196 f.Any suggestions!!
     
  2. Aug 3, 2018
    47v6

    47v6 junk wrecker! Sponsor

    Washington DC.
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    little more specific about what the problem is?
     
  3. Aug 3, 2018
    tarry99

    tarry99 Member Sponsor

    Northern California
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    Sounds fuel related.........maybe filter, blockage in the line.....maybe a vent problem...at fuel cap or in tank..........take the line off from both ends and blow some air through it to make sure it's clear , change the filter, take the fuel tank cap off and run it again while off.....

    Ignition could also be in question..........not sure what you have? but some ignitions when hot will just break down....
     
  4. Aug 3, 2018
    David329

    David329 New Member

    Va
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    Thanks ilI check the fuel lines and ignition
     
  5. Aug 6, 2018
    David329

    David329 New Member

    Va
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    Ok took vent lines off blew them out with air also took gas cap off fuel filter replaced fuel pump looks new still cutting off when it reaches op temp guess I'll have to start replaceing ing parts next any suggestions??
     
  6. Aug 6, 2018
    David329

    David329 New Member

    Va
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    It's is a77 cj5 258 inline 6 two barrel carb
     
  7. Aug 6, 2018
    tarry99

    tarry99 Member Sponsor

    Northern California
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    How long does it run before shutting off?............What is the temperature of the motor? Is it just idling then shuts off? and will the motor re-start again immediately ?
     
  8. Aug 6, 2018
    PeteL

    PeteL Member Sponsor

    Hills of NH
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    I would suggest you think it through in a logical step-by step sequence, testing each system, BEFORE starting to "replace parts."

    First of all, in most cases, should be a standard tune-up procedure to ensure everything is set to specification.
     
  9. Aug 7, 2018
    David329

    David329 New Member

    Va
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    When it first started cutting off I could drive it around for a couple hours.Now it will run for about 10 to 15 min's then cut off op. temp around 130 to 195 it will crank back up but takes several trys.If I let it sit for about 25 min's it will crank right up!
     
  10. Aug 7, 2018
    PeteL

    PeteL Member Sponsor

    Hills of NH
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    Coil? Do you get spark when it is in hot-non-starting mode?

    Vapor lock? Test for fuel pressure and volume when hot.
     
    heavychevy likes this.
  11. Aug 7, 2018
    tarry99

    tarry99 Member Sponsor

    Northern California
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    Ignition Type...........points or electronic?...........If points and condenser change them.......but first check the gap and see if there burnt or blue on the tip.........might also look at the condition of the lobes on the distributor.................As Pete mentioned above check the coil and all the primary wiring leading to it........Just for exercise I would also replace the cap and do a resistance test on the plug wires..........also What does the plugs look like? Have you done a compression or leak down test on this motor?..............And on the fuel filter did you install a clear one in line just before the carburetor? I've seen them get dirty one after another if your tank has issues............When it starts to die is it blubbering.......and filthy rich?.........is that choke working correctly?
     
    Last edited: Aug 7, 2018
  12. Aug 7, 2018
    TIm E

    TIm E Sponsor Sponsor

    NW Arkansas
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    There is also the possibility you are getting too much fuel (as Tarry alluded to) and flooding it out. When it dies, take the air cleaner off and make sure the choke is open. Then open the throttle once or twice while looking down the carb throat. If you see fuel squirting down in there, you are getting fuel.

    Next, have someone else start it and watch the carb to see if fuel is percolating up from the float bowl vent and down into the throat. This would likely indicate a bad float, float valve or incorrect float adjustment.
     
  13. Aug 7, 2018
    montanacj

    montanacj Sponsor Sponsor

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    Lots of good advice has been given. I’d check the coil for sure, there are various was to check it heres one.
     
  14. Aug 8, 2018
    David329

    David329 New Member

    Va
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    Thanks for the tips the coil has been changed also new carb the fuel system seems to be working ok. It has the electronic distributor so what's the best way to check that and the ing module?
     
  15. Aug 8, 2018
    tarry99

    tarry99 Member Sponsor

    Northern California
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    Take it to your friendly Local Auto Parts store...........call them first and make sure they have the equipment to make the check......also make sure you properly mark all the wires and location for the distributor.........So choke and float level are OK?
     
  16. Aug 9, 2018
    heavychevy

    heavychevy Sponsor Sponsor

    Danielsville georgia
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    It does sound a lot like vapor lock. Insulate your gas line to keep heat off it.
    One of the old time methods was to put several wooden closeline pins on the gas line to absorb the heat. Do this and if it runs fine you know what your problem is. If you do not have any, the various dollar stores will
    Engine bays, ( jeeps, mid engine vans, small cars) do not have enough cooling in them to always avoid this problem.
     
  17. Aug 10, 2018
    David329

    David329 New Member

    Va
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    I will give this a try. Would a electric fuel pump solve that problem?
     
  18. Aug 10, 2018
    heavychevy

    heavychevy Sponsor Sponsor

    Danielsville georgia
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    Vapor lock occurs when gas gets to a temperature where it vaporises. Some type of insulation to keep the temperature on the line is what you are looking for. This usually happens when your exhaust heats the line to a point to make it into a slow boil.
    I would not recommend this but years ago i had a chevy van (mid-engine) that would get hot enough the gas would boil in the carb. I borrowed a drill bit from a friend that would drill a hole tinier than a sewing needle. Drilled a hole in top of carb where it would vent. This was recommended by a mechanic that had worked on cars for 40 years. I do NOT recommend this to you, but it cured my problem.
    I know this will draw a lot of flac from the jeeping community by what i've said but it worked for me. The carb must be disassembled to do this and the utmost care to keep any metal shavings out of the fuel delivery system. THIS should be a LAST resort.
    Try some plumbers insulation first to shield the line to keep it the cooler. Now this was about 1973, lot of things have changed, mostly methods since then
     
    Last edited: Aug 10, 2018
    David329 likes this.
  19. Aug 10, 2018
    PeteL

    PeteL Member Sponsor

    Hills of NH
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    It can... if the pump is located as a "pusher" not a "puller. Sucking from the engine end reduces pressure in the line and can encourage vapor formation. Pumping from the tank end adds line pressure and discourages vapor.

    BUT since learning you have electronic ignition, I'd be very suspicious of that first. They can fail weirdly and unpredictably.
     
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  20. Aug 10, 2018
    OldAdobe

    OldAdobe Sponsor Sponsor

    Lassen County, CA
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    I had a cj7 with a 4.2. Owned it for 20 yrs. Does your CJ have a fuel filter with a single or dual outlet on the carb side? A Dual outlet filter is a for a return to the tank which among other things can help to circulate fuel thus may reduce vapor lock. If the cj has dual outlet filter, try orienting it with the smaller outlet higher than the larger outlet that connects to the Carb.
     

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