Yamaha Guys- fuel pumps

[Bass Cat]

I have 94 200hp 2.6L V Max, It is on a boat with an electric fuel pump with the mechanical pumps still on the motor. My question to the Yamaha guys is: Should these mechanical pumps stay on the motor with the electric pump inline. I know this was a long thread with the Merc guys and nobody ever really said why to remove or not. Personally I don't see the need for the mechanical pumps while running the electric. Feed back needed please. How do you have your Yammi setup? By the way the oil system has been removed and running pre-mix 40:1.

[VectorPat]

I dont see any reason for the Mech. pumps to be there other than for back-up if the elec. craps out...If you remove them just be sure to plug the holes going to the crankcase...

[vector mike]

I would think that if you left them on there then it could only flow as much as the stock pumps will let go through and not getting the benefit of having the high volume of an electric fuel pump.

[Bass Cat]

Now we're getting somewhere, Thanks Guys. If any one has done this could you post or email a pic and tell how you plugged up the holes. I just want to do it right the 1st time.

[TD]

just bypass the stock pump and leave it in place so you dont have to plug the holes? Just plug the lines from the mech instead?
TD

[Markus]

I used to have both the diafragm pumps and a Carter pump in place, but removed the diafragm pumps after someone said the pressure of Carter + diafragms might be enough to open the needle valves in the carbs. Did (to my knowledge) not experience it, though.

However, plugging the holes is simple - all you need is some screws - M8s, if I remember correctly.

[Ray Neudecker]

We have run them both ways with no real difference except the plumbing was easier when we left them on. A 6mm bolt will fill the hole or covers can be fabricated to bolt in place of the pumps. I prefer the covers if not taking apart to do. Hate the thought of putting thread shavings into the crankcase while tapping.

[Markus]

M6. I stand corrected.