Summer89

So I have a standard regular mechanical block mount fuel pump. Not sure if it's ever been rebuilt. Past couple times I've pulled my bilge plug I'm getting a somewhat concerning amount of oil that came out with water, and more then a drip or 2 from hoses etc. So I looked and my fuel pump is kinda covered in oil starting from the top by the vacuum hose. Doesn't look like it's comming from the block seal or anything. So is this thing on its way out or what? Not sure if it's original or not. Would it be better to rebuild or replace. Still confused why it's leaking oil. Also on the carb it seems the vacuum hose is connected to the ported vacuum hose nipple on the carb. Is that right? I just took a random holly photo for reference .

BillK

The inside of the pump is exposed to engine oil. If the diagram gets a leak in it or gets loose where the two halves of the pump go together it will leak oil. It might also be leaking where the pump is bolted to the block. If the tube you are talking about on the carburetor goes to the fuel pump it is actually an overflow tube that is meant as a safety device in case the diaphragm in the pump breaks. It will start pumping raw fuel into the carb and cause the engine to run terribly or stall completely. This lets you know there is a problem with the pump. Normally there should be no fuel in that hose. Post a picture of your actual carb.

Summer89

Well I got a few things going on. I can get actual pics tomorrow. One pic is off the holly page. And it's hooked to the timed port on the side of the bowl Vs. full vac port on the bottom. Someone told me it should pull vac all the time. The next 2 pics are of what style pump I have that does not appear to be stock. Can't tell if mine was painted or bought black. Well the hardin one says I need a regulator and I don't have one. But then I find this other one that is self regulated. I dont have an inline fuel gauge so I don't know my pressure. I guess I got some digging to do. Like I said I can get actual pics tomorrow. I'm just wondering if I can even get a rebuild kit for these pumps.

BillK

As far as I know the line from the pump does not go to a vacuum fitting BUT I have not done a marine Holley in a long time so I could be wrong. I am used to Quadrajets and they have a dedicated fitting for that line. Most Holly setups I have seen have the safety tube going to the flame arrestor. I am sure someone else will chime in. If not i will find out for sure in the morning at the shop.

Either way under normal conditions there should never be any fuel or oil in that hose.

SB

Do not hook the mech pump fitting to vacuum. This will reduce fuel psi. Yes, you read that correctly.

The fitting is in case of rupture. This should be routed to over the carb. Usually thru flame arrestor or somewhere over the carb.

Summer89

I have an fittings and lines. There is a small capped port by the carb hard fuel line that is for a gauge. That's where I would go for my pressure gauge.

Summer89

It doesn't regulate it does it? I thought it was for an emergency leak. Even if hooked to the pcv or af it would still pull vacuum. I wonder if it pulling vacuum is what caused the oil leak?

BillK

I just did a quick search and found this picture. If you look closely you can see the line going from the fuel pump to the flame arrestor. That is the only way I have ever seen it done with a Holley carb.

Summer89

thanks for verifying. My airfilter doesn't have any port. Maybe i could add a add to it or something. Think I could add it to my pcv vents or would that still be too much vac? My pcv is hooked to the back bottom of the carb

BillK

You DO NOT want it hooked up to vacuum . . . . period. Is your Holley a marine carburetor ? What part number is it ? You probably need to try and find a flame arrestor with the fitting. What do you have on there now for a flame arrestor ?

Some pictures of your setup would really, really help a lot with trying to get you a solution.