1988 Mercury 115 will not throttle up

[tlamos]

Two summers my boat did not get put in the water.I started it up seemed to run fine until I brought it to the Lake,it idles fine but when you throttle it up it dies out.Brought home took all the old gas out put in fresh gas same problem.I then took it to a boat shop they tore down all the carbs and cleaned them.These carbs were rebuilt 3 summers ago by a mercury dealer.I also had all hoses and primer ball replaced by the dealer.Put it back in the Lake same thing happens.I then played with primer ball I noticed the ball did not stay hard
so I purchased a new one intalled it same problem.Once I start to throttle up the engine will start to die I will hit the choke and sometimes it gets me past the dead spot,once I get past that spot it runs very strong. I also rebuilt fuel pump,I then took it back to the lake it ran perfect, better then it has ran for a long time.I thought my problems were fixed.A couple days later I took it out again it started the same problem over again. The only thing I did was gas it up. Anybody with any ideas that I can try?
Confused in Vermont

 

[hkeiner]

Re: 1988 Mercury 115 will not throttle up

You might consider using a pressure gauge to to see if the fuel line pressure between the fuel pump and the carbs is up to spec when the motor is bogging. You might also consider using an inductive timing light or inductive meter on the spark plug wires to see if the spark is OK when the engine is bogging. Troubleshooting tests help narrow things down. It is easy to spend lots of money replacing parts on a wrong hunch when systematic troubleshooting could have helped find the problem before buying the unneeded parts. Just my opinion...

 

[AutumnKash]

Re: 1988 Mercury 115 will not throttle up

I had a similar issue with my 1989 Mercury 100. When I tried to pull a skier, I had no power. The funny thing was that if I took it up on a more controlled acceleration there was no problem I found the issue to be an old cracked hose from the on board gas tank to the motor. I replaced a section of hose where the crack was and everyting was fine. I guess I was sucking air under hard acceleration.

I hope this works for you.

 

[Flossyb20]

Re: 1988 Mercury 115 will not throttle up

Check the quick disconnects at both the tank and the engine, sounds like one of them is clogged up or no good. You can verify this by running the fuel line directly to the fuel pump from gas can.