Johnson 20R72R

[Thomasiboats]

Was given this 20hp engine. Has good compression, spark, and I cleaned carb and replaced gas lines. I can run it at a slow idle, but I can't seem to crank throttle handle far enough so that the roller actually pushes on the throttle cam to allow a full throttle. I adjusted the roller to start between the two lines, the cam marks, as specified in Clymer manual. When I crank the handle as far as it will go, it only barely starts to move the mechanism and doesn't allow me to rev engine. However, I can push the mechanism freely with my fingers. Ideas? Thanks! Tom

 

[racerone]

Motor has to be in gear for full throttle !

 

[Thomasiboats]

But I can't even throttle it up at all when I am attempting to start it. It will start, and run at low idle, then I try to give it some gas, there is no travel in the twist of the handle at all. Just barely makes an audible change and that is already as far as it will go. Might the twist handle need adjustment?

 

[racerone]

??----But there is a shift interlock !----It prevents you from winding this motor up in neutral.----Or maybe the nylon pin at the bottom of the towershaft is broken..----Or the motor is running on one cylinder.----Bring it over as this is easy to figure out.

 

[Thomasiboats]

Where ru located? Where is the towershaft so I can take a pic and post? Thx very much for ur reply. Tom

 

[F_R]

The interlock is located on the starboard side of the powerhead. You can see it move as you move the shifter handle. Looking at the upper end of the interlock, you can see how it limits throttle movement in neutral and reverse gears. If it won't start and run within the limitations, there is something else wrong. That "something else" list is lengthy if you don't understand all the possibilities.

 

[Thomasiboats]

The interlock is located on the starboard side of the powerhead. You can see it move as you move the shifter handle. Looking at the upper end of the interlock, you can see how it limits throttle movement in neutral and reverse gears. If it won't start and run within the limitations, there is something else wrong. That "something else" list is lengthy if you don't understand all the possibilities.

Ok guys. I can see that mechanism and it functions properly. I have only worked on smaller motors and they did not have this. Thx a ton! Saved me a trip to marina. Tom

 

[oldboat1]

You are back on track then, right? Post back to confirm operation -- might require some additional tweaking. Make sure the water is well above the pump for testing.

BTW, in your initial post, you seem to be saying that you are opening the carb while the timing plate was not moving. That's a bad idea in that you could invite a runaway engine. (Check operation of the carb linkage with the engine off.)

 

[Thomasiboats]

You are back on track then, right? Post back to confirm operation -- might require some additional tweaking. Make sure the water is well above the pump for testing.

BTW, in your initial post, you seem to be saying that you are opening the carb while the timing plate was not moving. That's a bad idea in that you could invite a runaway engine. (Check operation of the carb linkage with the engine off.)

Yes, thx for that advice. I am actually waiting on a water impeller kit, but if I have more issues, I won't hesitate to ask. Thx! Tom