Fuel pump leaking oil !?

[b8kedbeans]

Here is a new one to me; I have a massive oil leak (In my 88 L 4 speed) that only happens when I am on the freeway or city driving under high acceleration/hill climbing (San Francisco).

I have been trying to track down the source of the leak for a long time. I replaced the oil sending unit, crank and cam seals, head gasket, valve cover gasket, etc. but the car still spews oil under acceleration. I finally decided to hunt this problem down once and for all so I started by putting cardboard between the motor and firewall in strategic places to determine if the oil is coming from above or below the head gasket. Wet on top, dry on bottom. I have a leak from above the head gasket. I then cleaned the motor and wrapped various suspect parts in clean papertowels and taped them in place. After another test drive I see that the oil appears to be leaking from the fuel pump. Finally, I am making progress! So i removed the fuel pump and reinstalled with new gaskets. Another test drive shows the oil is still leaking and appears to be coming from the vent hole in the fuel pump.

Has anyone ever seen this problem before? I assume that oil is coming out because there is higher than normal crankcase pressure so I just replace the pcv valve and am hoping that after replacing the fuel pump the problem will be solved. If anyone has any helpful advice at this point then please do share. I would hate to spend $50 on a fuel pump and have some high-pressure engine condition just blow out the diphragm or seals in the new unit and be back to where I am now but $50 poorer.

Thank in advance!

[25Horseplay]

Fuel pump leaking oil on a 93? Not gonna happen, the pump is in the tank.

[worfdog]

i have had this happen before, but it was on a carbed festiva. mine was leaking out of the weep hole onthe pump.but as 25Horseplay stated, your profile shows you having a 93 and it should have the pump in the tank.

[b8kedbeans]

Uh, yeah forgot to mention this is my 88 L 4 speed. But thanks for the reality check! I just picked up a used fuel pump from the pick-n-pull to swap in for the leaky part. If the replacement is not also faulty I will finally get to see if I have nailed this issue. fingers crossed... and thanks Brian and Worfdog for the replies!

[25Horseplay]

Makes sense now.

[b8kedbeans]

Update, with the used fuel pump installed the oil leak seems to be gone but unfortunately the pump leaks gas (doh!). The good news is that I can be fairly sure that buying a new pump will fix my oil leak. Man what a pain this has been. I have been through all of the old posts regarding oil leaks but could not find any that mentioned the fuel pump as being a possible culprit. Even google only returned a few relevent hits and it seems like oil leaks from fuel pumps are almost always a classic chevy problem. Live and learn.

[b8kedbeans]

Final update, with a new fuel pump there are no longer any problems! No fuel leaks no oil leak. In addition, the car runs very well now as I can imagine there were issues with low fuel pressure and possibly other pressure/vacuum issues that were related. Lesson learned: A fuel pump can be the source of both fuel and oil leaks.

[scitzz]

Man, that is sweet, at least it did not cost you an arm and a leg! You even went about the diagnosing in a fairly reasonable manner. I like it(notice my sig).
Glad she is back up and running!