Can you remove the mechanical fuel pump on 500efi's. My dads 2005 Formula 370ss has both the mechanical pumps and the electric. I know there are issues with the mechanical pump that is driven off of the sea pumps on those motors. My 2000 Fountain also has 500 EFIs but no mechanical pumps. So would the formula work ok without?

Merc added them due to a large number of boats that experienced vapor lock...particularly the starboard motor where the fuel system was between 2 hot engines. Because of the fuel/oil issue with those pumps I removed mine and drilled/tapped a fill and drain hole so I could change the fluid in them without removing them....(simply buy extra drive fluid in those little soft bottles).

The reason these are there because they suck/pull gas from the gas tank to the electric fuel pump. Electric do not suck/pull gas from the tank very well. Mecr tried to cure vapor lock with the VST system which is another story.

I knew about the vaporlock issue. I just wondered if anyone had done this and had any issues after removing them.

I know a guy on here a couple weeks ago was having problems getting an electric pump to pull from the tank. Maybe if the pump is mounted lower than the tank??

I can tell you from experience that it won't work on my 575sci which is the same electric pumps on he later 500efis fuel cool. My mechinical pump fell apart internally, my electric would run most of the day but stop pulling by the end of day and cause loss of fuel pressure above 3000 rpm. Drove me nuts trying to figure it out.

Change the oil, and keep stabilized fuel in the lines over the winter and you should have a problem. You can also remove the assembly and dump the oil out and refill out of the boat, I found it much easier to change the oil using that method

Now that's ingenious!!
Any pics of that setup??

never took any pics.......but there is one hole in the side of the pump that is accessable (barely). I think it's at the top of the "fill" area so I drilled/tapped a fitting at the bottom of that space (only about an inch lower that the fill hole). I bought a brass fitting from Lowes for a plug.
I've since sold the boat but the new owner thought that was pretty cool too.


Obviously you have to do this with the pump off the motor.

Thanks everyone for the advise.