I've got a '74 fuel pump that has been sitting for a long while without any gas in it. Before I go to the trouble of mounting it in my car, I want to make sure the seals are OK. Quoting Brad Roberts: "Time and time again, I have soaked the pumps in gas.. and had the seals come back. They shrink when they dry. Doesn't mean they failed, they just shrunk. Most people flip out when the pump is leaking. Put it in a bucket of gas for a few days"

Anyone done Brad's trick? Does he literally immerse the entire pump in the can of gas?

I can confirm that the seals do expand with gas. They are a rubber o-ring. I've taken a pump apart and the o-ring won't go back in place until you have totally dried it out and shrink a bit.

That said - soaking it in gas is not a magic bullet. But if it is a dry seal sure - gas will help it out. Not sure if I would throw the entire pump in gas - it just doesn't sound right. Can't back that up with any fact or theory.

I would think you'd just want to soak the pump head in gas. The motor can filling up with gas just doesn't sound like a good plan.

I searched for a source for replacement fuel pump O rings. I found one and they sent a sample. It seem to fit. Problem was they have a $25 minimum order. I have a lot of fuel pumps that I have taken apart to free up and am leery of reusing the o rings.
Bruce

Bench testing them is not a bad idea. Find out if it works/leaks before you install it in the car.

Any time you ever need an O ring to swell, soak it in Diesel fuel. It would also be a good idea to run diesel through you pump just before storing it. It has a more oil/solvent base and will not evaporate as quickly as gas.
Gasoline vaporizes at -45 degrees. Diesel Vaporizes at 150 degrees.

Diesel will cause almost any rubber to swell and will ruin vacuum pumps (just incase you have one)

I would think you could make up the 25 bucks pretty fast with selling "re-sealed" fuel pumps. Or you could sell extra O-rings here. If you know what size they are I have a few places that stock metric O-rings with no minimum. (BTW usually metric spec will be like P-90, S-90, Etc, with the letter being the cross section.)

Uhhhh ... the motor on the pump is cooled by the gas flowing through it. Soaking it in gasoline will not hurt the motor if the seals are not leaking.

On newer cars with submerged pumps sure, never heard of it on an external pump.

put the pump with the inlet and outlet ports facing vertically upward and fill the pump with gas thru the ports. No advantage to submerging the pump in gas.

any chance the source also had rubber for the pop off valve tip?

OK - like the sound of standing the pump up and filling with gas. Now the newbie (newbier?) question.... what's the best way to bench test it? Obviously hook up the pump to a battery, but I want to make sure I'm testing it like it would be used in the car and with 3 ports I'm not sure what the proper steps should be.

3 ports

S= feed (from the tank)
D= deliver (to the engine)
R= return(to the tank)

each port should be marked with raised plastic letters near the ports..

yes it works, it is my trick,!!!!

took about three days of soaking in a big coffe can of gas, but it sealed it up (tested each day thats how I know it took three days not two.)

give it a try, once installed, keep checking it for a while beofre you decide to park the car inside however, juct to be sure, but yes the seals can swell back up to seal.

however i figured why risk it and bought a new one anyway.

but yes it does seal after a soak, and yes, just dump the hole pump inot a can of gas.