1983 mercury 9.8 no full throttle.

[Chrislambing]

Hi all,
I purchased a 1983 mercury 9.8 motor a couple of months ago and am experiencing some issues. First of all, the motor fires right up after 2 or 3 pulls, the motor will rev to wot. In neutral but when I put it into forward it seems to only want to go to half throttle. Even when the tiller handle is turned all the way to fast. Every once in a while it will run like a champ and will go full throttle with no issues, but most of the time this is the issue I experience, any help would be much appreciated. New to marine engines over here!

 

[ondarvr]

What it does in neutral doesn't mean anything, it may sound good even if it's in terrible condition.

Check to see if it's running on both cylinders.

 

[tpenfield]

:welcome:

If you can describe a bit more about the condition of no having WOT, that would be helpful. Even the worst of engine will reach full RPM in neutral.

Maybe you can post a video of it running on the boat.

I would check the ignition wiring as mentioned. Also look at the condition of the wiring in general.

 

[Scott Danforth]

could also be crud in the carb. get a carb/fuelpump kit

also check for spark

 

[racerone]

Maybe a plastic thingy on the throttle shaft is broken and out of position.---Or the venturi is missing.----Sorry I can not see , hear or feel your motor.

 

[Chrislambing]

Thanks for the replies, when I twist the tiller handle to the fast position it basically doesn't do anything.....no spit, spider, anything like it's stuck at half throttle, it has new spark plugs and seems to have spark. Every once in a while the motor will all of a sudden perk up and run like a champ for a while then will die back down. I will try to upload a video the next time I'm out.

 

[Chinewalker]

Classic symptoms of running on one cylinder. With the motor running and exhibiting the problem described, remove one plug wire at a time. I'll bet one of two things will happen - either the motor will continue running with no change, or it will stop completely. Both would indicate motor only running on one cylinder. Let us know what you find.