15 HP Evinrude wont plane

benji2682

Recruit
Joined
Dec 20, 2004
Messages
3
I have a 76 15HP Evinrude pushing an 80s something Sylvan jon boat. I cant get the boat to plane. Motor runs excellent. I can feel it start to push the boat when I gun it but acceleration stops at about 1/3 throttle while rpms increase until the motor is running wide open. I suspect something is slipping although that is a rather uneducated guess. Any theories, test or help in general would be greatly appreciated.<br />Schluter
 

phatmanmike

Captain
Joined
Oct 24, 2003
Messages
3,869
Re: 15 HP Evinrude wont plane

it is possible that you are only running on one cylinder.<br /><br />you need to do a compression and spark test before we can conlude anything else.<br /><br />also, when the motor is WOT, are you sure that the butterflies are opening all the way?<br /><br />check these and get back to us. i have a 1988 15hp wich is almost identical, so i can help you greatly.
 

OBJ

Supreme Mariner
Joined
Dec 27, 2002
Messages
10,161
Re: 15 HP Evinrude wont plane

Hi Schluter...welcome to iboats.<br /><br />Your problem sorta' has overtones of a spun prop hub. Are you saying that as rpms increase the boat dosen't go any faster or it slows down maybe to a stop? When ya' check out what Mike posted above, pull the prop and put a reference mark on the inside hub...you can see the rubber hub on the inside. Make the mark from the rubber hub to the metal hub of the prop. When the motor does the high rpm thing again, pull the prop and see if the lines are still lined up. If they ain't, prop hub is spun. Take it to a prop shop and get it rehubbed....
 
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