Electric fuel pump installation Question
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Junior User
Joined: Jan 2006
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Electric fuel pump installation Question
I have a 1979 F350 crew cab with a 400cid equipped with a motor-craft 2 barrel carburetor. I am thinking of installing a holley low pressure (red) electric fuel pump in series between the fuel tanks and the mechanical fuel pump on the engine. My question is, at higher speeds or when under a load, pulling a heavy trailer will the mechanical pump be able to draw enough fuel through the electric fuel pomp if it is not on in order to meet the demands of the engine while under this kind of load?
Changing the intake manifold and carburetor to 4 barrel is not an option.
The only time I want to run the electric fuel pump is to prime the carburetor after the vehicle has been setting for a while, or when switching fuel tanks. I also want the electric fuel pump to serve as a back up in the event the mechanical quits working.
Thanks
Changing the intake manifold and carburetor to 4 barrel is not an option.
The only time I want to run the electric fuel pump is to prime the carburetor after the vehicle has been setting for a while, or when switching fuel tanks. I also want the electric fuel pump to serve as a back up in the event the mechanical quits working.
Thanks
Fleet Mechanic
Joined: Feb 2010
Posts: 1,742
Likes: 5
From: Near St. Joseph,MO
I don't know that the mechanical will pull fuel through the electric or that the electric will pump through the mechanical. There's a reason nobody uses both. Is that electric one not strong enough to replace your mechanical completely? Does the stock mechanical not put out enough fuel? I don't understand why you are fixing a problem that isn't there. I've never had an issue with not being able to prime.
Posting Guru
Joined: Aug 2010
Posts: 1,761
Likes: 8
From: Knoxville, TN
The mechanical pump is positive displacement - if it can't prime, it's got a bad diaphragm and needs to be replaced. Like the other Brian here, I don't see the point in trying to run both - pick one or the other and do it right, rather than trying to patch a problem that may or may not exist.
Fleet Owner
Joined: Dec 2009
Posts: 20,678
Likes: 83
From: NorCal
'Could be plumbed in parallel to the mechancial system with a check valve at the head end and a gate shut-off/selector at the tank.
No opinion whether it is a good idea or not.... your time, your money,, and your truck.
No opinion whether it is a good idea or not.... your time, your money,, and your truck.
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