87 Johnson outboard throttle problems?

[PierRat]

I have a 1987 Johnson outboard that is getting stuck when giving it 3/4's to full throttle. When I try to back off the throttle it keeps accelerating even in Neutral until I turn off the ignition to kill the engine. Luckily this has only happened running on muffs in the driveway but now I'm afraid to take it out.

Also this started happening after I was adjusting all of the idle and linkage adjustments to resolve a loss of reverse problem I had encountered last time I had it out. I thought I had it just right when it was shifting properly again in forward and reverse without grinding or bogging out in a test tank, but now this.

I just want to know what to focus on so I don't create the prior problem (no reverse) again by messing with the wrong adjustment.

Any help would be greatly appreciated.
Thanks, Jesse

 

[PierRat]

Re: 87 Johnson outboard throttle problems?

Anyone???

 

[dew2]

Re: 87 Johnson outboard throttle problems?

Tiller or remote? HP?

 

[boobie]

Re: 87 Johnson outboard throttle problems?

Model # ???

 

[PierRat]

Re: 87 Johnson outboard throttle problems?

sorry, it's a 40 HP MODEL #J40TLCU... any help would still be greatly appreciated.

thanks,
Jesse

 

[jonesg]

Re: 87 Johnson outboard throttle problems?

You should never go above high idle on muffs because there is no load on the engine, it will spin up and run-away.
Its easy to throw a rod doing that.
Submerge the leg in a barrel to provide exh backpressure and keep it under control.
Still...its not good to over-rev in neutral even with backpressure.

Your engine is probably running prefectly fine, its the pilot who's in error.

 

[PierRat]

Re: 87 Johnson outboard throttle problems?

Thank you for your quick response, I do have a test tank and I have heard it said that running it off the muffs alone was bad at high rpm's just didn't know that was what would happen with no exhaust back pressure. Hopefully I haven't caused any permanent damage. Both times I did this I would kill the engine immediately because it sounded like it might blow up if I let it go any longer. I will try to run it in the tank first thing after work tomorrow just to make sure. Thanks again - Jesse

 

[jonesg]

Re: 87 Johnson outboard throttle problems?

If you can, put it in gear, should idle around 650-700 at idle in fwd.
On the hose that will jump to 1100 and wander around,
mine quits on a hose but ticks like a clock in the salt.

Theres another condition that can happen on a hose if the engine has carbon buildup, the carbon gets hot enough to cause ignition without spark and causes thermal runaway,
turning the ignition off doesn't stop it .!
It will deisel on at high rpm until you choke the carbs.(a rod goes out the side).

Theres so many quirks to running an outboard I think the service book should be called the owners manual.