'99 Ficht

[Peter3708]

Ok so I bought the boat with a 99 175 Johnson Ficht. The motor has been running great--except, @ 4000 (+/-100) RPM's we get this strange non-rythmic knocking from the motor that may or may not be missing at the time of the "knock". It sounds like someone is hitting the motor cover with a wooden dowel rod? Any ideas?

 

[Mod2]

Re: '99 Ficht

Moving to Johnson/Evinrude forum.

 

[The Marine Doctor]

Re: '99 Ficht

Might be detonation of a piston.<br /><br />TMD

 

[seahorse5]

Re: '99 Ficht

What is your top rpm with an average load? If it is below 5600, get a different prop to allow the motor to turn 5800-5900 range.

 

[Peter3708]

Re: '99 Ficht

Top end is 5600+ but not by much. The knocking sound sounds like it might be a computer issue??? but it is loud and only at 4000rpm.

 

[seahorse5]

Re: '99 Ficht

There were minor and major updates to that motor over the years, along with software changes. You may need the services of a KNOWLEDGABLE tech to find out what your motor has.<br /><br />What spark plugs does the silver EPA tag near the serial number plate say to use?