Half Throttle in Froward

[bryans1]

1971 18hp Evinrude with new points and condensers revs to full throttle in neutral and even runs full throttle in reverse. However, when in forward it will not open up (only goes half throttle) even though the throttle linkage is wide open/all the way down just like when in neutral or reverse. Any ideas are appreciated.

 

[James R]

Re: Half Throttle in Froward

Look at the gear shift interlock mechanism that prevents going full throttle unless in gear. Could be incorrectly set.

 

[bryans1]

Re: Half Throttle in Froward

My interlock seems to be fine in that it does allow full throttle in reverse and forward. I am getting full power in reverse, but half power (at best) in forward.

 

[Rick.]

Re: Half Throttle in Froward

Sounds as though JR is on the right track. I just wanted to add you shouldn't rev. the motor to full throttle in neutral. Forward and reverse is OK as long as your in the water with your boat. (not in a barrel) Not good for it. Good luck. Rick.

 

[bryans1]

Re: Half Throttle in Froward

What's odd is that it that the gear shift interlock mechanism is allowing the same range of full throttle in both forward and reverse (not neutral - I mis-spoke). However, the difference is that the engine rpms is about half in forward vs. full power in reverse when I open it up to full throttle.

 

[Rick.]

Re: Half Throttle in Froward

I read through my manual last night and there is nothing in it pertaining to the problem as you describe it. One long shot I thought of is....Could the fuel line be pinched when you've got it throttled in forward? I am assuming in forward your engine is designed to go fastest and therefore the armature plate will be turning further than in Neu. and Rev. This is a perplexing problem. Rick.

 

[James R]

Re: Half Throttle in Froward

Two things. The forward gear is not meshed correctly and binding. Two, as the gear ratio for the forward gear is different to reverse you are applying more load. could be compression, could be wrong plugs,could be carburation, could be fuel starvation,could be too big a prop.

 

[Chinewalker]

Re: Half Throttle in Froward

I'm betting it is the motor itself, running on one cylinder. Load is different in reverse and may give the appearance of "full" throttle. If compression is good and even, check for spark. Might be as simple as a blown head gasket or dirty points....
- Scott