F 12 fuel pump rebuild question

stumpman · Sep 21, 2012

To do a basic rebuild do you have to remove the pump from the engine or can you do it while it is still mounted to the engine? Is there any other reason the pump gets gas to the glass bowl but will not pump gas out of the other side? Could there be something clogged up maybe? I have never rebuilt one of these pumps and know little about them.

Thanks
Dennis

Tom Fleming · Sep 22, 2012

Dennis, the fuel pump is not terribly difficult to rebuild. There are 2 different diaphram configurations in these, and depending upon which one you have will deternine the rebuild kit you get. One diaphram is held on with a threaded piece, another one has what amounts to a pressed "rivot". In either case, you need to disassemble before you buy your rebuild kit. Both can be repaired/rebuilt, but the one with the threaded assembly is MUCH easier to deal with.

Also, rebuild kits are available, but get ready for sticker shock......although they are less expensive (significantly) that buying the whole, rebuilt assembly. Rice Equipment is Pa has the kits. Here is another excellent source, and they rebuild them for you as well:

http://www.classicpreservation.com/fuelpumpkits.html

Take it off and disassemble to determine which style you have. Unless you are really ham-handed, you are not going to ruin anything. Also, you will need to remove it from the engine.

stumpman · Sep 22, 2012

Thanks!

Tom Fleming · Sep 22, 2012

Dennis, one other thing that can go bad on these is the push rod that actuates the pump. These wear over time (as does the cam) and if there is not enough movement to "work" the pump, that will need attention as well. I don't have the exact amount of travel you should have on the pump rod, but I'll try to look it up.

I am sure someone here has either the correct new rod length, or how much travel it should have. As the rod wears, what you will see is a decrease in the GPM output of the pump. this becomes a problem when the flow falls below the consumtion of the engine. Since these have a by-pass built in, it would take alot of wear to get to that point, but it is something else you can check.

teddy52food · Sep 22, 2012

The rod length is 7 to 7/18 inches. Travel is about 3/8 inch.

Craig45 · Sep 23, 2012

Just rebuilt my pump, got the kit from rice equipment. They will
ask you what the check valves look like so you get the proper
kit. It was easy to overhaul. There are two springs that are
different size so watch where they go. My rod travel was 5/16
and it pumps well.

stumpman · Sep 23, 2012

Thank Y'all!

F 12 fuel pump rebuild question

stumpman

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Tom Fleming

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stumpman

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Tom Fleming

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teddy52food

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Craig45

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stumpman

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