40482 Fuel Pump Questions

[Thomas S.]

Replacing a leaky fuel pump on my 67 -427/400. Lots of awards on this one and I assumed the pump was original. It's not and I picked up a NOS AC logo 40482. I know production of these stopped decades ago. The arm is very hard to move, is this normal?

Can these be pre-tested with air pressure and if so, recommended PSI?



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[Gary B.]

Re: 40482 Fuel Pump Questions

The bolt boss on the casting, should not have a flat on it, nor should it have the rib on top. The flats started with early to mid 1973 fuel pumps and the rib stated late 1973 production. It should look like the picture below.
Gary Bosselman

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[Gary B.]

Re: 40482 Fuel Pump Questions

To answer your other question about pressure, I've been working on an early 68 L89, with the carburetors flooding out. All three pouring fuel out. After putting new needle and seats in twice and still getting the same results, I removed the metal line going to the rear carb and installed a fuel pressure gage at the "Tee". The gage showed 18-psi just turning over, cranking, not running. I changed the fuel pump with a repo, non-AC from Zips, it showed 14-psi turning over, just cranking the starter. I left the pressure gage in, the engine started, ran smooth, idled down to 750 RPM. At idle, the pressure showed about 13 to 14-psi.

Before starting the car, I checked the dipstick. I showed 2-quarts over full. That shows how much fuel was bypassing the needle and seat. I change oil and filter before starting the car.

So my answer is somewhere between 13-14 and 18 psi is the magic number. I'd like it closer to the 13-14psi number if not a little lower than that....

If you find a NOS and/or a non-used fuel pump, the diaphragm will still be good. A used pump, especially with ethanol fuel being used in it, will get as hard as a rock, generating higher fuel pressure.

Gary Bosselman

[Thomas S.]

[Peter M.]

Re: 40482 Fuel Pump Questions

I don't have a 68, but the 67 service manual says 5 to 6-1/2 psi. I think even 13-14 psi is high. Just my thoughts, which aren't worth much.
Kind regards.

[Thomas S.]

Re: 40482 Fuel Pump Questions

I have a 67 not a 68. The question I had was the pressure for testing the pump and it never occurred to me to check the operating pressure shown in the repair manual. Even with that spec, there has to be some value above that to compensate for various conditions. I'm not looking to do a stress test, just a leak test, so using the operating pressure should do the trick. Thanks for the reply.