1982 Mercury 90 hp loses power no top end

i have a 1982 mercury inline six cylendar motor that doesnt get up to max speed. lately it will take off then bog down to a slower rpm.

Re: 1982 Mercury 90 hp loses power no top end

I would do a compression check. you can get a tester from Autozone for like $20.00 deposit

Re: 1982 Mercury 90 hp loses power no top end

Does squeezing the primer bulb make any difference when it bogs down?

Mark

Re: 1982 Mercury 90 hp loses power no top end

Good thread... having the same issue with same outboard right now. Started a compression test, got to the third cylinder when the battery started to die... expected as this battery is upwards of 5 years old. Anyways, the third cylinder was about 10 lbs lower, with the first two checking in at 124 lbs. By researching, it leads me to believe if it gets worse, there is a gasket problem or possibly piston ring problem. Any insight? Links to helpful threads maybe? Anyways... just as a quick reference... what would you rate a piston ring replacement/ head gasket replacement at on a scale of 1-10 with 10 being impossible? Thanks for the help guys, and moodman be sure to change out as much as you can before you get into the deeper factors. Start with the fuel lines, primer bulb, filter, gas, spark plugs, plug wires, etc... see what you can change in your garage before you see what you can pay the repair man!!! (even though he has to make a living as well!!!)

Re: 1982 Mercury 90 hp loses power no top end

Since you said the battery was dying I would take the 10lb lower compression with a grain of salt. As log as they are within 15lbs of each other you should be ok, unless they were all really low. Reringing that engine I would rate a 7. On the other hand, changing a cylinder head, rate that a 10. There is no cylinder head gasket because that engine does not have a removable cylinder head. What a lot of people think is the cylinder head on these motors only in reality a water jacket cover.


Original poster... Are any of the carbs leaking fuel out a vent on the top of the carb?