Fuel Pump rebuild instructions - or lack of

[Richard G.]

I was lucky enough to have the original fuel pump on my 63.
It was of course, needing a rebuild.

This week I just received my fuel pump rebuild kit and went to install it.
The instructions that came with the kit are directly out of the 1963 GM repair manual.
That might be fine if the "diaphragm rod seal" type was identical to the original, which it is not.
No information on seal direction or how the seal goes together. Lovely.
Didn't mention this seal has to be installed and then the rod inserted.
Didn't mention if this seal should be greased.

After completing a YouTube search I came up with nothing, a Google search found this:

http://tech.corvettecentral.com/2013/09/1955-1966-corvette-fuel-pump-rebuild/

Instructions were for the same kit and it included actual pictures and installation information. Kudos to Corvette Central.
And, no my parts didn't come from them but the next ones will!

I have a spring force checking tool. The original Large (rusty) spring was 16 pounds at 1" height and the new replacement spring was 20 pounds at the same height. The way I understand the pump function is; this spring sets the fuel pressure. Original spring likely is damaged and week as it is 54 years old. But no way to prove it one way or another. At least it was the same length as the original. The shorter and smaller diameter spring was not the same length. (pictured below) I am going to use the original spring even though the instructions caution you not to.

I am including pictures of the original parts and the parts from the kit below;



Not the best customer service from the original vendor.
The paperwork had their name on it so I know it didn't come for the kit manufacture.
Rick

[Timothy B.]

Re: Fuel Pump rebuild instructions - or lack of

Richard,

My thoughts are the top oil/fuel seal is non directional, just install the retainer shown on the right in your photo as the pressure spring uses it as a seat. The orientation would be seal then seat then pressure spring.

I would use the new pressure spring with the new diaphragm. If the old lever is not egged shaped I would use it with the old spring, if not I would compare the geometry carefully then do as you suggest and use the original spring with the new lever.

Get a piece of 220 wet sand paper and on a flat surface broach the pump mating surfaces before assembly.

I agree with your theory on how the pump operates, it's very simple so take your time and try to compress the diaphragm half way before you tighten the round of screws.

[Frank D.]

Re: Fuel Pump rebuild instructions - or lack of

I agree with Timothy...you just have to be a bit careful....if you have a WCFB (250hp) or AFB (300/340 hp)...they don't like much over 5-1/2 lbs fuel pressure.... If the original spring worked fine before, it should still work...

Be sure to stake the poppit valves in.. If the diaphragm rubber is also a factor in pressure...many kits have thicker replacements.

[Richard G.]

Re: Fuel Pump rebuild instructions - or lack of

Thanks for the comments.
What the factory instructions left out is the seal has to be installed (pressed in) and then the rod for the diaphragm pushed through the seal and hooked to the lever. The seal can only be installed one direction as the steel retainer holds the seal in-place and fits into the depressed area of the seal. This would have been more obvious if I had pictured the steel retainer with the other side up. The old seal had failed and was no longer in the correct location when I pulled the pump apart. It is not obvious if the seal is made to flex with the rod or slide on the rod. I believe it flexes up and down with the rod and is not designed to be sliding on the rod. I plan on Loctite the steel retainer in place.

Thanks for the comments on fuel pressure. I will measure it when I get this started and report the results afterwards.

GM took care of a lot of details that the aftermarket does not really seem to care much about. Dealing with these issues seem to be a big part of restoring these old cars and getting them to function as they should.
Rick

[Richard G.]

Re: Fuel Pump rebuild instructions - or lack of

Below is a picture of the installed seal. The seal is installed first, then the tin retainer. Note; The seal is 1/16" smaller than the 1" counter sunk hole in the pump. The the metal retainer is installed by pressing it in. I used Loctite instead of staking the retainer.
The fuzzy part is a very crude filter that GM installed in the housing. Behind it are two holes that vent the pump to atmosphere pressure. On can see where pressure washing, this area, could allow water into the top of the fuel pump diaphragm.

[Richard G.]

Re: Fuel Pump rebuild instructions - or lack of

"Get a piece of 220 wet sand paper and on a flat surface broach the pump mating surfaces before assembly".

Mine bottom half mating surface was in terrible shape. I chucked it up in the lathe and cleaned it up.
I should have taken a picture before and after. Night and day.
It has been mentioned before the casting may be cast in slightly different materials, or maybe a better description would be "alloyed differently", because the bottom half of the matting surface was in much worse shape than the top.
Rick

[John D.]

Re: Fuel Pump rebuild instructions - or lack of

Richard, Is your rebuild kit for ethanol? John

[Richard G.]

Re: Fuel Pump rebuild instructions - or lack of

The vendor specifically indicated the kit parts were ethanol compliant.

The 340HP pump failed from no use and really old fuel. Kind of rusty looking inside.

I have a 64 Chevelle and it had the original fuel pump. when it failed I pulled it apart.
The valve material had decentagrated, I am sure it was from the ethanol as the valve pieces were de-laminating.
I have yet to rebuild that pump.

Actually I was surprised how easy it was to reconnect the rod for the diaphragm, got it on the first try.
My advice is to clean the pump up and go for it.
Only real issue was the condition of the parting surfaces (clamping the diaphragm)
That I cleaned up on my lathe. Would have been a pita to do with sandpaper but I am sure it would work.
I just tend not to have the patience for it. Guess that's why I purchased a lathe.
Rick

[Perry M.]

Re: Fuel Pump rebuild instructions - or lack of

I too have a lathe so I am trying to picture how you would chuck it up.

[Richard G.]

Re: Fuel Pump rebuild instructions - or lack of

It was easy, with a three jaw. Both the ports cleared the jaws just fine. Of course this was the lower half only, top half was fine. It's back together or I would post a picture. Rick