2 years ago I replaced my 502mpi mechanical fuel pumps and put new bearings and seals on the sea pump housings.
I pulled pumps to put in New impeller kits yesterday and change gear lube. My STBD pump has quite a bit of fuel mixed with gear lube.
I would not think the mechanical pump woyld be bad already with about 120hrs of use. I thought I had read somewhere here a bad VST diaphragm could send fuel to sea pump. Is this possible?

Some fuel in the mechanical pumps is pretty normal. I've never had one that didn't get some fuel dilution in the lube.

Best is to change Oil all 20-25 hours! Michael

I'd be looking at the diaphragm of the fuel pump.

Happens all the time , change it when you change your oil.

As mentioned, they all do it. I recommend to my customers to change it every 25 hours or so.
Eddie

Can the VST diaphragm send fuel to sea pump, or only the mechanical pump?