I have a 27 hp mini kohler and was riding yesterday. The motor at full throttle would rev up and slow down. Sometimes it would not do it at all. Does anyone know why it would do this? Thanks.

so, your saying the motor is reving but the boat is loosing speed while it does it?

Ya, not very good at explaining this stuff. When at full throttle the motor sounds normal and then it will lose speed and sounds like the motor is about to die but doesn't. Like the motor is not getting enough gas but there was plenty in the tank. Thanks.

Is your vent open? Sounds like either the vent is closed or you have an air leak in your line somewhere.

So, the motors rpms are surging and dropping?

The vent is open slightly, but maybe I need to open it more. As far as the rpms go didn't notice anything. It was just reving up and then going down like if a governor was kicking in and slowing it down. It was unbearable hot and ran it all day and didn't start doing it til the end.

Mine did the exact same thing. I had tank up front, 5/16 line, & new bulb, but had to pump bulb while running wot. Never tried an e-pump with it, but bet it would fix it.

Do you know where I could get one and the cost? Thanks Camo. I'm at 10 hours now, how do you check the belt tension?

If you were running it all day i would bet you formed a air lock from the heat. Mine does it from time to time and just have to give it a few mins to cool down and back to normal.

Mine was doing it during duck season, so I doubt it was vapor locked from the heat, but that's a good point right now. You can get an e-pump from Napa or any other parts store. Get one with 1-3psi pressure. Depending on brand name & where you get it, could be $40, could be $100.

Camo would you only worry about a e-pump when your dealing with a larger hp motor or are they good to have on small ones to.

E-pump is compensating for problems elsewhere. I've seen em on 16 hp long tails, at the same time, my MB 5000 is running on primer bulb & stock mechanical pump.

Mine will only vapor lock in the summer, but in the winter if i dont prime it real well, or let it warm up real well it will cut off about the same spot every time.

i just put an e pump on my 23 la special. Mica at mudbuddy recommended it cause my tank is up front. was supposed to help my idle and take the dead spoy out when I first hit it.. didnt work, but if my manual pump ever quits, ill still be motoring back in instead of paddling in. its still a good investment

There are 2 different types of pumps, some are "push" pumps & should be mounted inline near the tank (because they push) & some are "pull" pumps & should be mounted on the transom. If you put a push pump on the transom, it won't function properly. The "dead spot" or flat spot that swamprat mentioned is a common problem with most stock carbs.