Mercury 1990 15 HP outboard

[MK522fins]

Hi i have a 15 HP 1990 Mercury outboard that runs really good i can start it at the first or second pull. in neutral it runs fine but if i put it in gear it it will go in the slow position but when i speed it up it just runs the RPM's up and it will try to go but wont go more then 1-2 MPH. i cleaned the fuel pump because before when i would speed it up it would stall out. what would be the first thing i should look at?

 

[Maxz695]

Re: Mercury 1990 15 HP outboard

You say the engine rpms increase when you give it gas but the boat doesn,t go? The propeller may be spun. Make a mark on the nut and a mark even with it on the prop run the motor in forwards and then check the marks to see if there still in line.

 

[MK522fins]

Re: Mercury 1990 15 HP outboard

i am pretty sure the propeller is spinning because if i put it in a tank its pushes water out but it is not pushing any weight.and for some reason it drives in reverse fine. now im not sure why it would it does that

 

[Maxz695]

Re: Mercury 1990 15 HP outboard

jsut because it,s spinning does not mean it will when it has a load on it do as suggested to be sure

 

[quicktach]

Re: Mercury 1990 15 HP outboard

Sounds like the bushing in the prop is gone ! With the motor safely off, put the motor in forward gear. Can you easily turn the prop ?
I'd be inclined to try a new prop before digging too much further.

 

[MK522fins]

Re: Mercury 1990 15 HP outboard

yeah i can turn it one way pretty easy and it makes a clicking noise, but if i try to turn it the other way it wont turn at all

 

[quicktach]

Re: Mercury 1990 15 HP outboard

I've seen props you can't move with your hands, but under load the bushing slips and no power gets transmitted to the prop. I'd try a new prop or at least one you know works ....maybe you can get a lender from a dealer in the area..then buy if it works. If with a new prop, you still don't go, then you're into another problem.....the gearcase or upwards. Before you spend bucks, you may want to look down behind the carb to where the gearshift linkage goes down to the lower unit. This is the spot where you disconnect the lower shift linkage from the vertical shift shaft when you're going to drop the lower unit. Take a look to make sure a screw or clamping link hasn't come loose and you're ending up not moving the vertical shaft that goes to the lower unit ...or not moving it enough.