40hp yamaha 2stoke, barely moving

[miami2stroke]

Hi, very new to boating, I have a 1985 40hp yamaha stroke on a 14ft whaler.

When we bought this from the guy we knew it had things to tune up and replace, but we took it out with him and it really got going, nice speed. Since then we, had problems just running it from the very first time. replaced the water pump and a new throttle cable. We took it out today for the first time, thinking we were good. We got going but really didn't get close to the speed we know the boat can go. We could see the throttle was opening all the way, so i don't think its a timing thing.

We can get it into idle, then we throttle it all the way and it doesnt get much faster than that slow idle speed.

example: If the boat can do 30mph, I'm guessing it's doing 6-8

we have a million things floating around our heads about what to do, clean the fuel injection? Oil gas mixture issues?

Thanks for reading, anything would be helpful givin my very limited knowledge and experience with boating

Eddie

 

[bgbass.1]

Re: 40hp yamaha 2stoke, barely moving

Did you do a compression check as well as a spark check? also carb could just be dirty may need to be rebuilt. bad gas you should also do a decarb. and buy a manual

 

[miami2stroke]

Re: 40hp yamaha 2stoke, barely moving

Thanks I'll look into those things. We have a manual. How expensive is the tool to check compression, how important is it to own one?

 

[micel]

Re: 40hp yamaha 2stoke, barely moving

You can buy one at discount auto today for $29 thats right on accurate.Both cylinders should be with in 10% of each other.Pep-boys has the deep creep by sea-foam to de-carb it.Both places has ngk plugs for like $2.Tonight look under cowl(has to be very dark) and see if you see any fireworks around plug wires,if so replace.

 

[miami2stroke]

Re: 40hp yamaha 2stoke, barely moving

Thanks, I will check out pep boys for those items