Unknown fuel delivery issue
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Tuned
Joined: Sep 2018
Posts: 364
Likes: 22
From: Eagar, az
Unknown fuel delivery issue
So been working on this for a while, thought I would try to run a few things past you guys. Truck bogged and lost power after flooring it and getting up to about 50mph. After coasting a few hundred feet it all of a sudden was back on. Started looking at stuff under the hood and noticed fuel violently churning in inline filter during idle. Then it stopped and was calm like always. About 10 seconds later it started churning again, building up in violence and dropping the fuel level until it slows down and fills back up. This constant cycle lasts about 20-30 seconds and starts over. During the worst low level/hardest churning my carb bowl gets depleted and sometimes sputters before coming back around again. Fuel pump is mechanical with less than 100 miles on it, pickup is in good shape, and still new looking removed steel lines and steel wooled them- looking good, replaced small rubber sections between lines, filter after pump is new, regulator is a POS Mr gasket dial- set wide open, into a Holley 4412 on a fe390. Any ideas? Sometimes the pulses at the inline filter are hard enough to break apart the paper element-hence the new filter
Cargo Master
Joined: Nov 2007
Posts: 2,238
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Sounds like the regulator is the issue to me. I'd take it out, you don't need it with that carb and fuel pump. i ran the same setup on my 400M, tank>pump>filter>carb for years without an issue.
Looks like the FE has a bolt on fuel pump eccentric. Maybe that could be messed up?
Looks like the FE has a bolt on fuel pump eccentric. Maybe that could be messed up?
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Tuned
Joined: Sep 2018
Posts: 364
Likes: 22
From: Eagar, az
Yes I thought of the centric. I replaced timing set a few years ago and forgot to locktite the bolt and Install that outter ring bearing sheath thing, but my engine didn't have it already, so left it off. Carb says optimum is 6.5 lbs and max 7.5. I am running at about 8lbs. So got a regulator. Stock 2150 carb ran without one for 45 years, until one day I overflowed fuel all over engine during a Hot takeoff, figured pressure overtook needle.i hear horror stories about that regulator, so I will try removing that to see what happens.
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Tuned
Joined: Sep 2018
Posts: 364
Likes: 22
From: Eagar, az
Removing the reg did nothing. Took apart engine, and eccentric is cherry still. Pump arm has almost zero wear. I am gonna try an older pump I have lying around. Can't remember why I swapped it over winter, but I kept it as a spare. Besides that I am lost.
5th Gear
Joined: Nov 2024
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Alright after a few weeks of fighting with this I have an update. A lot of time off with the cold weather.
I ended up going with the above suggestion and getting a rebuilt carb from National Carburetor. Put the carb in fired her up, and I have gas flowing out the top, adjusted the float level and gas was coming out like a fountain.
At this point I find it hard to believe my issue is my carb unless my rebuilt one and my old one have the exact same issue?
I ended up going with the above suggestion and getting a rebuilt carb from National Carburetor. Put the carb in fired her up, and I have gas flowing out the top, adjusted the float level and gas was coming out like a fountain.
At this point I find it hard to believe my issue is my carb unless my rebuilt one and my old one have the exact same issue?
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