leaky fuel pump - ideas?

[MTribe]

I rebuilt my TR6 (mechanical diaphragm type) fuel pump and it leaks like a sieve! Maybe 2-3 drops/second. It does pump fuel fine to the motor. It looks like the leak is coming from somewhere underneath the flange of the pump. Definitely not the inlet and outlet fittings.

Any common problems with fuel pump rebuilds? Anyone have a similar experience and come up with a solution?

Thanks...

 

[Brosky]

If you rebuilt it, then you replaced the diaphragm, right?

If you did, you had to push the rod down through the seal in the bottom pump housing that keeps oil out of the pump, and fuel out of the engine, if the diaphragm leaks. It sounds like you have a pinhole in the diaphragm and it's leaking by the seal.

Better make sure that you engine oil isn't diluted with gas.

EDIT : Added pictures

 

[Brosky]

A dumb question, but, are the six (6) screws holding the cover and body together tight?

 

[MTribe]

Interesting... yes, the screws are tight... checked those.

I wonder if it is leaking through that hole on the diaphragm. I recall the shaft that goes through there had a sharp edge, maybe it tore the seal? It seems like that'd leak gas into the engine, but not out of the housing? Is that right?

Oh, hadn't thought about the engine oil thing.. I'll check that!

 

[Brosky]

The only way for gas to leak from that hole either outside or into the engine, is if the diaphragm is leaking internally.

You might want to remove the pump and pull it apart again.

 

[MTribe]

BTW, I got a $40 universal electric fuel pump from Kragen--worked great! Just hooked it up to some fuel tubing in parallel to bypass the other system. Got me through the 100 miles I needed to drive the car when I moved! Go Kragen. Need to address the mechanical pump eventually, though.

 

[Adrio]

I had this exact problem last year and it is a pain. You can look in the archives for the thread on it.

The bottom line for me was the new fuels that have ethanol in them will eat through the new diaphragms that come with the rebuild kits. I went through five diaphragms from three different sources. In the end one supplier came good and said they can't solve it yet but they gave me a new fuel pump as a replacement for the defective diaphragm. I installed it just at the end of the driving season last year and have not started driving yet this year (sad story about a boat with a few large holes in it) so I can't comment on how well it works.

If you take your diaphragm out and look at it right away (before the fuel dries too much) you will see small cracks or bubbles in the surface of the "rubber". It is obvious they were "atacked" chemically.

I still hold out hope that there will be a solution and I will be able to go back to the original pumps.