2001 75 hp 4 stroke Mercury losing top end pwr. not planing

[nitro640]

My 75 hp 4 stroke engine loses power at wot. It only runs at about 3000 RPM's at WOT. Also, when I pump the primer bulb it eventually picks up and runs fine until you stop and fish for a while. Then the primer bulb has to be pumped again while at WOT until it picks up again. Then it runs great until I stop again. The primer bulb does not remain firm after it is pumped and left for a moment. Any help would be appreciated. The carbs have already been rebuilt. Did not fix problem.

 

[WillyBWright]

Re: 2001 75 hp 4 stroke Mercury losing top end pwr. not planing

Welcome to iboats.<br /><br />The problem is could be a bad fuel pump. Or the fuel pump isn't able to pull the gas for some reason other than being a bad fuel pump. Check every component between your gas tank and motor from the screen at the bottom of the fuel pick-up tube in the tank, to the fuel pump itself. Those are pretty reliable pumps as a rule, but mechanical things can fail. More often the antisyphon valve, primer bulb, or fuel pump check valve can be fouled by debris from the tank.

 

[bigiron]

Re: 2001 75 hp 4 stroke Mercury losing top end pwr. not planing

Recently I had a similar problem and had to pump the bulb frequently. I finally took it to the shop and they replaced (of all things ) the tank to motor gas line. Apparently crud built up in the quick connects. Just a suggestion.

 

[nitro640]

Re: 2001 75 hp 4 stroke Mercury losing top end pwr. not planing

I checked all the components from the tank up to the fuel pumps. The problem ended up being leaky primer bulb hoses. After trimming the ends on the hoses and reconnecting them the engine ran fine. Top speed today 47 mph. Thanks for the replies.