1990 40hp Evinrude Boggs down @ 1/2 throttle

[rabalais8179]

I have a 1990 Tracker Party Barge with original 1990 40 hp Evinrude. I don't have the model number on hand. Took it out Saturday, ran all day, 10 gallons of gas, no problem. Then Sunday morning after 5-10 minutes at WOT motor slowed down and started jumping. So I brought back down to idle and slowly gave it throttle. At about 1/2 she started jumping again. Had to drive at 1/4 throttle the rest of the day. I had two spark plugs on boat, changed them and no difference. This coming weekend, I am going to replace the hose, bulb, and fuel filter and check gas for water. Just trying to gather information and parts before going down to try and fix. Boat is at lake. If I have any questions I may have wife get on interent. I appreciate any help.

Thanks
Tony

 

[Daviet]

Re: 1990 40hp Evinrude Boggs down @ 1/2 throttle

Was the motor jumping or did it sound like it was missing?

 

[rabalais8179]

Re: 1990 40hp Evinrude Boggs down @ 1/2 throttle

It was jumping up and down. As if I was standing at the back of the boat and pulling the motor up, but it wasn't doing it so much that it was coming out of the water. Also, the ball was not staying hard. Thanks for replying.

 

[Daviet]

Re: 1990 40hp Evinrude Boggs down @ 1/2 throttle

With the engine running the primer bulb will not stay hard like when you pump it up before starting. The jumping in and out almost sounds like a worn clutch dog jumping in and out of gear, the more power applied the worse it gets. You might check the lower unit oil and see if any metal particles in the oil.