1960's Evinrude 25hp Randomly Idles down when at WOT

[made3188]

I just boat this motor and when running at WOT it will randomly idle down, so I lower the throttle until it catches back to itself, then it will take right off again.
It might do it once every 20 min or 2 times in 5min.
My friend says he thinks it is the rubber in the prop, or a carb issue.
any thoughts would be great.
Thanks

 

[jbjennings]

Re: 1960's Evinrude 25hp Randomly Idles down when at WOT

You may have a weak fuel pump, or an improperly set float. Either way, it sounds like it is running out of fuel. Try pumping the primer bulb when it powers down and see if that has an effect on the problem. If so, check the fuel pump or carb float.

 

[AlTn]

Re: 1960's Evinrude 25hp Randomly Idles down when at WOT

if the speed of the boat drops, yet the rpms of the engine remain the same or increase, that indicates a possible spun hub in the prop. If the rpms drop from wot to idle randomly then jb's advice applies.

 

[made3188]

Re: 1960's Evinrude 25hp Randomly Idles down when at WOT

I took it out again last night and tried pumping the ball and it had no effect.
I also had some spray sea-foam and tried that while it was running but still had the same problem.
I am going to clean out the carb and check the float tomorrow and I will let you know how it went.
Thanks for the help.