johnson high speed problems

[boat800]

I have an 81 johnson 35, starts good, idles good and runs good until about half throttle. Ive cleaned the carb, new gas tank, new gas line, new gas pump. Good spark and compression 160 in both cylinders. The only way it runs full throttle is with the choke on. Any ideas...

 

[F_R]

Re: johnson high speed problems

You DID remove and clean the high speed jet...didn't you? It is deep in the hole behind the drain plug in the carburetor bowl. Even a hint of any gum or varnish in the jet's orifice will cause that problem.

 

[CATransplant]

Re: johnson high speed problems

Good question. Whenever someone says they "cleaned" a carburetor, I want to ask how they did it. For lots of people, it means they sprayed carb cleaner down the throat of the the thing and pulled the float bowl off and sprayed it, too.

As you say, his symptoms are exactly those of a dirty main orifice.

 

[5150abf]

Re: johnson high speed problems

Welcome to iboats.

you motor has 3 sets of jets, idle, mid and high speed, if you didn't clean out the jets you didn't clean the carbs, it takes suprisingly small amount of varnish to make a boat run really bad, it looks clean but it is restricted just enough to not flow enough gas.

Sounds like your high speed jets may be clogged, they are in the bottom of the float bowl, remove the drain screw and use a really skinny screw driver to get them out.

Once out use a stranded copper wire to run through them a couple times then reasemble and see if that gets it.

 

[boat800]

Re: johnson high speed problems

Thanks for the help, yes i did clean all the jets the first time and still had the problem. I ended up putting a larger high speed jet in by one size and for some reason its working great now. I dont know why the motor wont work with the original size jet but as long as it works i dont care...thanks again

 

[tashasdaddy]

Re: johnson high speed problems

have you or the motor moved to a different Elevation? that effects them.