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Engine shuts down

Engine shuts down

Cjman

Jeeper
Posts
35
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Location
Oceanside, Ca
Vehicle(s)
83 CJ7 258,D300,T176, D30,AMC20
New issue surfaced that comes and goes. The engine will idle for 30 min or more with no issues and I can drive it around with no issues. Then suddenly the engine idles well for a 3-4 minutes and suddenly you hear a change and the rpms drop and turns off. If I hold the idle speed higher it runs smooth and then after 1-2 minutes the RPMs start to drop even while I’m holding the throttle open. Sounds like running out of gas.

I thought water in tank so I siphoned as much as I can out. Placed 5 gal of fresh gas in with a bottle of Heet. No change. I replaced the fuel filter and no change. Today I swapped out the fuel pump and no change.

Thoughts? Thanks. G
 
New issue surfaced that comes and goes. The engine will idle for 30 min or more with no issues and I can drive it around with no issues. Then suddenly the engine idles well for a 3-4 minutes and suddenly you hear a change and the rpms drop and turns off. If I hold the idle speed higher it runs smooth and then after 1-2 minutes the RPMs start to drop even while I’m holding the throttle open. Sounds like running out of gas.



I thought water in tank so I siphoned as much as I can out. Placed 5 gal of fresh gas in with a bottle of Heet. No change. I replaced the fuel filter and no change. Today I swapped out the fuel pump and no change.



Thoughts? Thanks. G
Cjman
How old are your rubber fuel lines on top of the tank? The rubber degrades and the inner lining can seperate and act as a flapper in the fuel stream.
It can restrict flow causing EXACTLY the symptom you are describing.

If your lines are original think about replacing them all. Consider now if your going EFI or staying carb.

If your thinking EFI run two new vinyl lines now. When it comes time to do EFI your new lines will handle the higher pressure required.

If your still running a mechanical fuel pump you might want to pull that and see if it's in good shape or not.

Do you have oem fuel line setup with a return line and charcoal canister? Or was that all removed/modified?

If you dropped your tank, or tightened it up, you may have pinched a fuel line.

If your running a carb check your carb fuel inlet screens.

Cut the problem in half by running a 6' temp fuel line from a Jerry can to your carb. Run it and see how it goes. No issue proves the carb isn't the problem.

Then move the temp line to the fuel pump. Same test. If it works good then the fuel pump is ok.

Same at the stock filter location. If that's good it's time to drop your tank.

Sending unit pickup could be partially blocked.

Hope that helps.
Good luck.

Sent from my Pixel 2 using Tapatalk
 
Thank you very much for all the thoughts. I’m going to try several of the things your recommended. I recently changed the tank when I rolled over a branch and it lodged itself between the gas fill tube and the frame and it sheered off the fill and vent nipples. I replaced all the soft lines from the pickup including the lines going to the liquid and upside down check valves.

I’ll provide updates.
 
And did all the problems start after you put the tank back? If so I would drop it again and make sure a line isn't pinched.
 
Any update? Did you get it figured?

Sent from my Pixel 2 using Tapatalk
 

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