1989 Mercury 115 hp bogging down

[navymustang]

I have a 1989 mercury 115 hp. It was running great, then last week when I went on the river, I was at WOT and the engine suddenly bogged down, then picked back up. It continued to do this as i headed to my destination. When I stopped the boat, it died. I pumped the bulb and it started right back up. Went back up to full throttle, and ran fine for a few minutes, then started losing power again. Here's what I've tried so far....

1. Changed bulb......same problem
2. Ran new fuel line straight to tank (bypassed water seperator)....same prob.

It seems like it's burning the initial fuel that is pumped in with the primed bulb but isn't getting enough fuel after that.

The oil injection system has been removed and I'm mixing the fuel in the tank. But like I said, it runs perfect after I prime the bulb. But after a few minutes it starts to bog down then revv up.

Mike

 

[Unbalanced]

Re: 1989 Mercury 115 hp bogging down

How old is your fuel pump?

 

[Craigcat]

Re: 1989 Mercury 115 hp bogging down

The rectifier could have gone south, but it sounds like a fuel problem
If you suspect a piston seizing, its probly running lean, bad gas, or
plugs.

 

[navymustang]

Re: 1989 Mercury 115 hp bogging down

Fuel pump is probably original, and I don't know anything about the rectifier.(or what it does.) I don't suspect bad gas because it burns it just fine when I pump the bulb up, it's just after the initial flow of fuel is burned, that it starts to bog down. Also, it seems to idle fine. Is it possible that the fuel pump is weak? How can I test it?

 

[electricjohn]

Re: 1989 Mercury 115 hp bogging down

Try a remote tank and different fuel line. If that don't help, time to look at your 20 year old fuel pump.

 

[Lone Duck]

Re: 1989 Mercury 115 hp bogging down

Try a remote tank and different fuel line. If that don't help, time to look at your 20 year old fuel pump.

YUP!!

 

[reils_99]

Re: 1989 Mercury 115 hp bogging down

The same happened to me it would start, idle and troll smoothly...as soon as I gave her the gas...she would bog down....turned out to be a spun prop. Fairly cheap fix... Good luck!