1994 90HP V-4 frustrations

[TJEli]

Hi Guys,

I hope you can help. This motor is on a friends boat that we use for downrigger fishing. We are having a misfire problem.

When the motor is cool it will run pretty good. As we get a few miles into our run it will start misfiring and loosing power. If you keep running it will get to the point where it will pretty much only run at idle. If you let it sit for a few hours you can get another couple mile run out of it. We have tried several sets of new plugs with the same result. I need some ideas.

The motor is not oil injected and he runs a 50:1 mixture.

I also need to know the WOT operating range for this engine.

Thanks for the help,

-Eli

[TJEli]

BTW.... This is a Johnson.

Thanks again,

-Eli