81 mercury 115 starts and runs but wont get up and go

[chris 123]

I was at lake end of summer when thought I was low on fuel boat cut out while at 50 mph I cut throttle down a little and boat went back to normal so went back to dock filled tank went back out on lake was doing about 50 boat cut out and would only do about 10 mph changed plugs checked compression did spark check changed diafram on fuel pump can't figure out what's going on

 

[Texasmark]

Re: 81 mercury 115 starts and runs but wont get up and go

I had an '89 tower of 115. I ran 6000 at WOT. I had it on a Ranger bass boat. If I ran at WOT for a mile or so, same thing would happen. I essentially ran the engine out of fuel. I went through the trouble of installing an electric fuel pump and all since the tank was quite a bit lower than the engine but it was a hassle.

I fixed the problem by rerouting my fuel line and making it as short as possible.

HTH,
Mark

 

[chris 123]

Re: 81 mercury 115 starts and runs but wont get up and go

Thanks still not sure but soon as it gets a little warmer I'm going to do some tinkering an if not I will pay the big bill down at marina

 

[Texasmark]

Re: 81 mercury 115 starts and runs but wont get up and go

Thanks still not sure but soon as it gets a little warmer I'm going to do some tinkering an if not I will pay the big bill down at marina

Get on the squeeze bulb when it falters and feel it. It should be soft but have some resistance meaning fuel is being sucked through it. Then give it a few pumps and see if the engine recovers. If so new pump. If not, bulb, inlet fuel line, kinked fuel line or line too long, poor venting on tank for a few thoughts.

Mark

 

[canoemang]

Re: 81 mercury 115 starts and runs but wont get up and go

Verify all butterflys are opening and timing is advancing all the way at wot..

 

[James R]

Re: 81 mercury 115 starts and runs but wont get up and go

Have you changed anything prior to this happening. So many things that can cause this. Quick check on the sparks will help. If they look ok then is the motor idling correctly. From what you have said I would check that fuel is getting out from the tank. Blockages are quite common. How do I do this you ask. Get a separate container of fuel and put the tank end of the feed hose into it and take off. If it runs ok then you have a tank cleaning to do.

 

[quicktach]

Re: 81 mercury 115 starts and runs but wont get up and go

Motors starving for fuel. How's the fuel filter? Fuel tank vent OK ? Got a new fuel line ...one that's not rotting ?

 

[1979checkmate]

Re: 81 mercury 115 starts and runs but wont get up and go

i had this problem on my '79 TOP. The engine would occasionally run great and then fall on its face. It would also occasionally idle great and when i went full throttle it would try to, then fall on its face. i did fuel pump and carb rebuilds to no avail. The electronics were getting pretty nasty looking with the insulation rotting away and such so i decided to completely redo the ignition system. I replaced both the stator and trigger as well as the rectifier. I had to replace one of the switchboxes after further testing (these arent cheap...so i replaced with another used one.) the coils tested fine so i am still running originals. Anywho.. after working on ignition i have never had an ounce of trouble with the motor.