1992 Johnson 120 HP Stalls

[joeltjen10]

I recently rebuilt my carbs, had a power pack replaced, and put in new spark plugs. I'm still having an inconsistent issue while trying to get the motor started after it's had time to cool off.

I will start the motor using choke with the idle lever up, once its started I will put the idle lever back down and it will stall out. The next time it may do the same thing but it doesn't stall when the idle lever goes down, so I put it into gear and it stalls. The last scenario I try to get it to work is putting the idle lever down and instead of a slow starting throttle I put the throttle all the way down and it still stalls.

Finally, I tried putting the idle lever up and letting it warm up for 20-30 seconds and it will run well until it cools off again. This issue didn't happen before the carbs were rebuilt, the power pack was replaced and new spark plugs were put in. I rebuilt the carbs first so I don't believe it was happening after that either but it could have been masked by the issues caused from the the power pack being bad.

Any help is greatly appreciated!

 

[James R]

The indications are that one or more cylinders are not working. Try removing the plug wires one at a time and running the motor. If a cylinder is not working there will be no change in performance. Did you do a compression test. If the compressions are good the next thing to do is a spark test. Sparks should be capable of jumping 7/16 gap.. If all this is good then back to the fuel. Use a spray bottle filled with fuel mix and spray fuel into the carb throats while it is running. If the motor picks up you need to find out the fuel problem.

 

[joeltjen10]

The indications are that one or more cylinders are not working. Try removing the plug wires one at a time and running the motor. If a cylinder is not working there will be no change in performance. Did you do a compression test. If the compressions are good the next thing to do is a spark test. Sparks should be capable of jumping 7/16 gap.. If all this is good then back to the fuel. Use a spray bottle filled with fuel mix and spray fuel into the carb throats while it is running. If the motor picks up you need to find out the fuel problem.

Thanks for the response. I actually had the shop do the diagnostics and repairs on the Power Pack. They said the compression checked out good. I suspected a fuel issue but wasn't sure where to start. I'll give the fuel mix spray a shot. I'm also going to bug the shop but wanted a second opinion.