fayjo56 Posted February 27, 2015 Share Posted February 27, 2015 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? Quote Link to comment Share on other sites More sharing options...
deadline Posted February 28, 2015 Share Posted February 28, 2015 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? Quote Link to comment Share on other sites More sharing options...
fayjo56 Posted February 28, 2015 Author Share Posted February 28, 2015 Thanks for your input, I will have to have a tinker and see what I can find, no i didnt put anything on the threads so this might be the first step. Quote Link to comment Share on other sites More sharing options...
thedawnpatrol Posted February 28, 2015 Share Posted February 28, 2015 I'm sure like a lot of old vehicle owners, I always prime the pump, with the primer arm before starting if it has stood for a while to save strain on the battery. Jules Quote Link to comment Share on other sites More sharing options...
gas 44 Posted March 1, 2015 Share Posted March 1, 2015 "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. Quote Link to comment Share on other sites More sharing options...
deadline Posted March 15, 2015 Share Posted March 15, 2015 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??? Quote Link to comment Share on other sites More sharing options...
fayjo56 Posted March 15, 2015 Author Share Posted March 15, 2015 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. Quote Link to comment Share on other sites More sharing options...
Tony B Posted March 15, 2015 Share Posted March 15, 2015 Could be the ignition breacking down. That can give kangaroo type symptoms. Also have you fresh fuel in the tank, and is it getting to the pump? Quote Link to comment Share on other sites More sharing options...
deadline Posted March 17, 2015 Share Posted March 17, 2015 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. Quote Link to comment Share on other sites More sharing options...
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