1990 120 HP Johnson V4

[CT-Kurt]

I have a 1990 120 HP Johnosn outboard on an 18' Boston Whaler Outrage. It appears one of the cylinders doesn't fire until the engine has been running for at least 10 minutes. After the motor runs the missing cylinder kick in and the motor runs fine. This happens well after the high idle warm up speed temperature is satisifed <br /><br />Any ideas. I have tried new plugs and wires <br /><br />Thanks

 

[JB]

Re: 1990 120 HP Johnson V4

Ahoy, CT-Kurt.<br /><br />I think you have an ignition component that requires heat before it will operate.<br /><br />You may be able to isolate this by running the engine on the muffs with the cover off and heating ignition parts with a hair dryer.<br /><br />The offending cylinder can be isolated when the engine is running, cold, by disabling individual spark plugs and noting any changes. When you pull the dead cylinder there will be no change.<br /><br />Good luck.