Johnson 1997 150 Looper
Engine stumbles intermittently at planing speeds, sit for a few hours, then may run good for 40 minutes on the run home or may run bad. Once in a while will totally die at idle after being initially idled 5 minutes - crank it, won't start. Runs again in about 5 minutes.
Idling high at 1100 rpm even when fully warm ( with motor in barrel or on water)
Idle timing is 10 degrees ADTC which should make it idle low.
Quickstart does not kick in even at a cold start probably because high idle speed tells quick start not to engage.
Here is what I have done.
Carbs rebuilt including new bowls. New plug wires, fuel lines, water separator etc etc.
Ran on remote tank - ran worse.
Timing at WOT tested on the water is 20 degrees BTDC - right where it should be.
Compression 90-95 - Decarbed once no change in compression.
Connector housing connecting 5 power pack wires to timing plate was partially melted and some wire insulation melted. So something got really hot around there. Connector contacts ok and wires were taped up so they are not touching.
Adjusted the carb throttle plates.
Played with the idle mixtures on the water with no significant change to stumbling problem.
Any suggestions appreciated.
Engine stumbles intermittently at planing speeds, sit for a few hours, then may run good for 40 minutes on the run home or may run bad. Once in a while will totally die at idle after being initially idled 5 minutes - crank it, won't start. Runs again in about 5 minutes.
Idling high at 1100 rpm even when fully warm ( with motor in barrel or on water)
Idle timing is 10 degrees ADTC which should make it idle low.
Quickstart does not kick in even at a cold start probably because high idle speed tells quick start not to engage.
Here is what I have done.
Carbs rebuilt including new bowls. New plug wires, fuel lines, water separator etc etc.
Ran on remote tank - ran worse.
Timing at WOT tested on the water is 20 degrees BTDC - right where it should be.
Compression 90-95 - Decarbed once no change in compression.
Connector housing connecting 5 power pack wires to timing plate was partially melted and some wire insulation melted. So something got really hot around there. Connector contacts ok and wires were taped up so they are not touching.
Adjusted the carb throttle plates.
Played with the idle mixtures on the water with no significant change to stumbling problem.
Any suggestions appreciated.