Boat jerks at high speeds

[zacklanders]

I recently had my 1986 Evinrude 90hp rebuilt including carbs. Runs good and planes good but jerks every few minutes intermittently. A mechanic friend told me it was the rectifier or trigger. I already replaced the stator. Can I unhook the rectifier wires running to stator and run it at high speed to check rectifier. Will I damage anything by doing this? It doesn't seem to want to kick in sometimes as if one of the cylinders isn't firing yet. When it kicks in runs great. Please Help

 

[Daviet]

Re: Boat jerks at high speeds

I Would start by using an inductive timing light, have a friend run the boat, and check spark when the problem happens. Check each cyliner for spark and see if there is a dead cylinder.

 

[coolguy147]

Re: Boat jerks at high speeds

might be gear case? jerking like does it seem to come out of gear like?

 

[petryshyn]

Re: Boat jerks at high speeds

I Would start by using an inductive timing light, have a friend run the boat, and check spark when the problem happens. Check each cyliner for spark and see if there is a dead cylinder.

I agree, could be a coil, plug or wire getting tired....

 

[jonesg]

Re: Boat jerks at high speeds

I recently had my 1986 Evinrude 90hp rebuilt including carbs. Runs good and planes good but jerks every few minutes intermittently. A mechanic friend told me it was the rectifier or trigger. I already replaced the stator. Can I unhook the rectifier wires running to stator and run it at high speed to check rectifier. Will I damage anything by doing this? It doesn't seem to want to kick in sometimes as if one of the cylinders isn't firing yet. When it kicks in runs great. Please Help

If the tach works its not the rectifier.

Trigger is always on the list of usual suspects but I wouldn't throw money at the problem, run through the tests in the manual for each component.