1986 115hp Merc full throttle issues

[khenke413]

Just took out my boat for the first time today after replacing the impeller and installing a fuel water separator and other maintence. When I took it out and took a quick lap it worked great. However, when I shut it off and started it back up it wouldn't throttle all the way up. The throttle would be all the way ahead in forward. But it couldn't climb all the way up into full forward, it cut in and out trying. Every once in a while it would throttle all the way up, but when I slowed and sped up it wouldn't throttle all the way back up.

 

[Chris1956]

Check compression and spark on all cylinders. If those are good, suspect dirty carbs.

 

[khenke413]

It will run in neutral just fine at full throttle. Is there an issue with my forward gear or fuel flow?

 

[Chris1956]

Running at full throttle in neutral proves nothing about the engine's condition, and can cause it to blow up.

If you have even compression on all cylinders, and spark on all cylinders, have someone pump the primer bulb as you accelerate and run at high speed. If that fixes the issue, rebuild the fuel pump, clean all fuel filters and make sure there are no air leaks in the fuel line.