Help, Mechanical Fuel Pump Not Working
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5th Wheeling
Joined: Apr 2023
Posts: 30
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Help, Mechanical Fuel Pump Not Working
It’s me again friends. Still working on an 85 f150 with an inline six 300… has a mechanical fuel pump… it wasn’t getting gas so I cleaned the tank and ran new hoses and replaced the sender… that fixed the fuel gauge (yay) but still no fuel getting to carb (boo). I disconnected it from the carb to see if it squirted, nope. I replaced the fuel pump, still not pumping. Even when I put a six inch hose on it and put that in a cup of gas no gas pumps out. I took the pump back off and I see the cam lobe in there moving… could it have ground down to where it doesn’t engage the pump enough? It looks smooth to me. Otherwise I’m out of ideas as to why it won’t work and need help. Thanks.
Mountain Pass
Joined: Oct 2019
Posts: 130
Likes: 31
If the eccentric on a cam is completely wore down the pump won't work find a way to turn the engine over by holding something against that eccentric that the fuel pump arm rides on and if it's not any movement it's rounded. Never heard of such a thing. What you could do is leave the bolts that hold the fuel pump loose but on there turn the engine over and see if there's any movement if nothing's moving the arm on the fuel pump you won't see pump trying to move. If no movement there's either the wrong fuel pump something wrong with camshaft on engine
FTE Legend
Joined: Nov 2015
Posts: 30,915
Likes: 4,123
From: Angier, NC
If you find the cam lobe is good I have to ask what size rubber hose did you use on the fuel system?
I had an issue with my 300 six when building and not wanting to put fuel in the tanks so I used along hose on the pump to a gas can on the inner fender above the pump and it would not pull fuel.
Me thinking the pump dried out when working on the truck and would not pump so I replaced the pump.
New pump would also not pull fuel from the gas can???
Thinking maybe the hose was not on pump good I used 2 clamps, still no pumping.
You know what fixed it?Using the right size rubber hose, 5/16" hose not 3/8"
Dave ----
I had an issue with my 300 six when building and not wanting to put fuel in the tanks so I used along hose on the pump to a gas can on the inner fender above the pump and it would not pull fuel.
Me thinking the pump dried out when working on the truck and would not pump so I replaced the pump.
New pump would also not pull fuel from the gas can???
Thinking maybe the hose was not on pump good I used 2 clamps, still no pumping.
You know what fixed it?Using the right size rubber hose, 5/16" hose not 3/8"
Dave ----
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