Mercury 35 hp only runs at about half throttle.

Hi, I'm new to the site and I hope someone here can help me.
I have a Mercury 35 hp ELO from around 1986 #1035717 on my pontoon boat. I have had it for 3 years and its usually a good running motor. Some times it doesn't want to idle however once I take it out on the lake and open it up it idles pretty smooth. I use seafoam in every tank. This is what it's currently doing. It does idle but going forward it only runs at about half throttle even though the handle is all the way forward. If I put it in reverse it seems to run wide open. Here are two changes that have happened this year that may contribute or cause this issue.
1. Because the water in the lake is so high this year it is a no-wake lake so I can't really been able to open it up. Although I have tried it still only runs at about half throttle. So maybe it's a carb problem?

2. The throttle/shifter is mounted to the side of my steering console. I modified the console (lowered it) then remounted the throttle/shifter in the same holes now at a lower position. Of course that pushed the cables down thru the floor. Could that have changed something?
Anyone have any ideas??

Have someone work the throttle as you see if the carb opens all the way.

Jeff

Thanks Jeff.
I will be going up to the lake this weekend and that's a good place to start.

Pat

What Jeff said; could be cables are binding or loose or not connected well to the throttle arm in the engine; that throttle arm controls how far the carbs open and how far the advance mechanism goes; carbs opening and advance are positionally synchronized.

RickM46 said:

What Jeff said; could be cables are binding or loose or not connected well to the throttle arm in the engine; that throttle arm controls how far the carbs open and how far the advance mechanism goes; carbs opening and advance are positionally synchronized.

Click to expand...

Thank you, will definitely check that out this weekend.