HELP! 2000 70HP Johnson Intermittent Loss of Power

lewatkin

Recruit
Joined
Jun 21, 2004
Messages
4
My engine experiences intermittent power loss. It will be running at WOT (5000RPM) and will suddenly drop down to 3500 RPM. I have found out that my lower cylinder of the 3 is not functioning when this happens, because when the problem starts, I can pull the third plug wire and it runs the same. If I continue running the engine at 3500 RPM, it will jerk as if it wants to go full RPM, but then dies back down. However, it will eventually jump back up to WOT at its leisure and then back down at its leisure. My engine seems possessed. I have checked: <br />--compression, and all 120 <br />--tried choking it during problems and engine boggs down normally <br />--sprayed fuel/oil mixture into carb and it didn't improve the cylinder <br />--pumped fuel line with no change in performance <br />--cleaned all electrical connections <br />--have replaced power pack and all plugs with no change. <br />Anyone, have any suggestions on where to go from here?
 

ob

Admiral
Joined
Aug 16, 2002
Messages
6,992
Re: HELP! 2000 70HP Johnson Intermittent Loss of Power

Try running it with the cover off and or examine the lower cylinder plug lead closely.On the 3 cylinder John/Rudes the sparkplug boot can sometimes find a ground through the motor cover latch.If that's not it you may have a failing ignition coil to that cylinder.Before just buying a new one ,swap it out with one of the others and see if your problem cylinder moves.
 

lewatkin

Recruit
Joined
Jun 21, 2004
Messages
4
Re: HELP! 2000 70HP Johnson Intermittent Loss of Power

I have tried switching the coils with no change. I will observe the motor cover latch. I have noticed that the latch is looser than it should be. Thanks for your reply? Anyway this could be the stator or something wrong under the flywheel to cause my symptoms?
 

ob

Admiral
Joined
Aug 16, 2002
Messages
6,992
Re: HELP! 2000 70HP Johnson Intermittent Loss of Power

Next item I would look at is the timer base.Obtain ohm reding as per manual specs.After that next item upstream is the pickup coil.Just make sure you rule out that latch before digging too deep.
 
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