I have a 34 PQ with 454 mags (385hp). 300 hours. Checked the oil level in the mechanical fuel pumps. The starboard was low, filled it, no gas. The port had a gas smell to it. The oil was still fairly thick.

2 questions:

Any idea on how bad the pump is based on the above description? What I am trying to judge is it shot, do I have a few hours...or is this common?

Any magic to replacing these units?

Thanks.

Jeff

Michigan

I had the same problem last week. Thanks to the advice I got here on OSO, I fixed it pretty easily. On mine, the gas must of been leaking a lot because the reservoir filled up and it started dripping out the weep hole into the bilge. The weep hole must be there specifically for that reason. It shouldn't be leaking at all. I would replace it immediately. Leaking gas is NOT GOOD. The fuel pump was $120. Get a new gasket too.

Dave M.

Checked the oil in the fuel pump??
What year 454 mags do you have?
I've never heard of this. Mine are 1991s. Should I be checking oil level in them?

Hey Payton,

On my 1997 454 Mag, the fuel pump sits on top of the sea water pump housing. There is a reservoir that lubes the mechanism that drives the fuel pump. There is 90 W oil in there. I never knew there was any maintenance required with this setup unless there is a problem with it. I don't know if the setup is the same on 1991's. There is a large flat head screw on the side of the pump were the lube can be added.

Dave M.

My 454 mags are 95. The fill is exactly where Dave M said.

I read a couple of posts when I searched and one guy said even after replacing the pump there still was a gas odor.

On mine one pump has an odor but the oil is still thick....

Jeff

Just to chime in on what the rest said, ANY fuel leak or seepage from the fuel pump is bad. It's only going to get worse. Drop the pesos on a new pump and be done with it. You'll be kicking yourself if you try to make this thing last and you wind up with a fire or explosion on your hands.

I've got a brand new pump on the shelf that I don't need. In the Merc box. PM me if interested.

John

I replaced my fuel pump last year on my '97 454 mag. What tipped me off that it was going bad was my fuel pressure guage wasn't holding steady and the pressure would drop off within a minute or so after the engine was shut off. I also found gas in the gear box upon removal. The pressure guage I relied on was an inline cheap one from Summit, and with the new pump the pressure held steady and long after the engine was off.

The older 454 mags ,gen4, have the fuel pump driven off the cam through the block.
Did the Gen 5 blocks have the new setup?

Yep, no place on the block to mount a fuel pump on Gen V's.