Seawater Pump with Mechanical Fuel Pump Maintenance

[alldodge]

If you have an engine mounted mechanical fuel pump which looks like this on your engine.


The pump could be leaking gas into the fuel pump cam mechanism and you may not find out for some time. In older days the fuel pump was mounted to the engine, and if it leaked a little bit, it would be removed when you changed the oil. See the vent port is low


With it being mounted on the sea water pump, the gas will get mixed with the oil and will cause wear of the seals and cam lobe. If it leaks slow enough you may never know until water starts coming in the boat from the seal failure. The reason for this is the vent tube when mounted on the seawater pump is higher. In order for the fuel to reach the tube it must fill the seawater pump cam housing and the fuel pump before it will reach the vent port.




The seawater pump in the picture above uses gear lube in the fuel pump cam area. The seawater pumps of this type can have one or two screw fittings. The one above has only one screw fitting, which is the fill port. If anything comes out when the plug is pulled you have gas or water leaking in. If it is water it will look milky, gas leak will thin the gear oil. If a little gas is found you should drain and refill with fresh gear lube. If you get more than just a little you should replace the fuel pump and inspect your seals.

Seawater pumps with two screws will have one on the bottom which is a drain. Those with only one will need to use suction to remove the oil from the top plug then refill.

 

[Fun Times]

Re: Seawater Pump with Mechanical Fuel Pump Maintenance

Seawater pumps with two screws will have one on the bottom which is a drain. Those with only one will need to use suction to remove the oil from the top plug then refill.

Some of the guys in the past would take the time to drill and tap a new hole to allow a second drain plug to be installed in order to make it easier to change the oil every year that really should be done as these systems seem to have an hidden tendency to allow fuel to seep into the oil on a regular basis.

The drain plug like found on the stern drives were found to work good.

Thanks for sharing.

 

[alldodge]

Re: Seawater Pump with Mechanical Fuel Pump Maintenance

Some of the guys in the past would take the time to drill and tap a new hole to allow a second drain plug to be installed in order to make it easier to change the oil every year that really should be done as these systems seem to have an hidden tendency to allow fuel to seep into the oil on a regular basis.

The drain plug like found on the stern drives were found to work good.

Thanks for sharing.

Very good point, and would be easy to do

 

[Grub54891]

Re: Seawater Pump with Mechanical Fuel Pump Maintenance

I personally dislike that setup. Seen to many that give up the ghost. And that poor belt,It works pretty hard turning that setup.
Grub

 

[tpenfield]

Re: Seawater Pump with Mechanical Fuel Pump Maintenance

Yup, I got those on my engines . . .

When I bought the boat, it was the first thing the surveyor checked, by opening the oil fill screw. Sure enough, a strong fuel smell.

So, the starboard engine got a new fuel pump. I plan to check them every year.

 

[alldodge]

Re: Seawater Pump with Mechanical Fuel Pump Maintenance

Mine was showing signs so I just replaced the pump this during winterization. This along with another guy here lost both, one was putting water in the bildge from lack of checking. I rebuilt the two pumps for him and it got me thinking maybe others may need to be reminded.