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Getting fuel up on Jeep.


fayjo56

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Although I havent used the Jeep out ans about yet, whilst tinkering, I have noticed that the 'head' of fuel at the carb seems to drop quite quickly, meaning quite some cranking of the engine to get fuel back up. Is this evidence of a problem? Would it be worth fitting a non return valve?

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Its normal for the fuel in the carb to evaporate after a few days, but if the carb is dry after a few hours it most likely means that the fuel pump internal valves are leaking or the seats are damaged/worn. If you have a primer arm pumping the primer to fill the fuel bowl is an available option.

 

A fuel pump repair kit is easy to find from any jeep vendor.

 

Also, you could have a slow leak at the threaded connectors (less likely), did you use teflon on the thread?

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"Also, you could have a slow leak at the threaded connectors (less likely), did you use teflon on the thread?"

If the threads are correct and good condition the "cone" style connections on pipework should NOT require ANY type of additional sealing. Saying that through, work related items I have had things come in from across the pond with so much sealer on that when trying to undo the brass fitting its been damaged.

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  • 2 weeks later...

NPT fittings should NOT require a sealant, but should use a thread lubricant.

 

Your answer hinges on two very improbable situations... that the threads of the pot metal pump housing are still in good shape and the NTP to flare elbow threads are also in good shape.

 

The hard lines should never leak via the threads.. they are sealed by the flare in the pipe itself. But the brass fitting into the pump and at the carb fuel bowl are the most likely places for leaks.

 

Lead paste was the lubricant/sealant of the day... so if you wanted to be 'internet correct' you could use that. But any paste type sealant would work and look correct. IIRC lead paste was red???

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All helpful stuff. At the moment she is firing up but 9 times out of 10 dies after a short while. I suspect a fueling problem of some sort, so am still tinkering. When I have managed to keep her going she runs ok, although tickover is a bit rough as though maybe running rich, so I think the fuel pump is ok.

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A vacuum gauge attached to the intake would help. There are many 'how to read a vacuum gauge' posts if you google it.

 

TM9-834 has info on how to read a vacuum gauge.

 

https://www.tm9-801.com/forums/viewtopic.php?f=1&t=1054&p=2301&hilit=vacuum#p2301

 

Just remember that a 4 cylinder motor will have a lot of bounce at idle.. don't confuse this with bad valves unless other issues also point to bad valves.

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