Yanmar 3GMF at 2600 RPM in neutral

[Jim Oursler in Rockwall]

Yanmar says that this engine should reach 3600 rpm in neutral.. I am only getting 2700.Cleaned mixing elbowReplaced filters.Adjusted throttle linkageEngine runs clean and smoothProp size isn't an issue.. again.. getting low rpms in neutral. Looking forward to the collective wisdom of fellow hunter owners. This is on a 1984 Hunter 34. Regards,Jim In Rockwall

 

[Wynn Ferrel]

Wrong tach?

I went through the EXACT same drill a couple of weeks ago. Turned out I had the wrong tach. When I took delivery of my 340 last November the tach didn't work. The dealer changed it out and he put in the wrong tach -- so Hunter is sending me a new one. Turns out everything in the engine was/is okay, just the tach putting out the wrong reading. Suggest you call Joe Kerr at Hunter. He did an excellant job of diognosing my problem from Florida to my boat by cell phone.Good luck,Wynn FerrelS/V Tranquility

 

[John K Kudera]

3GMF

I have been experiencing the same symptoms, along with the black smoke, and unable to get over 1800 RPM in gear.This past weekend I talked to a Yanmar mechanic, and he suggested I try this:With the engine idling, crack open the injector fuel inlet line (the line on the side of the injector)as if you were bleeding the lines. If the engine falters and starts to die, the injector is good, if you open the fitting and nothing happens, the injector is bad.Needless to say, I found a bad injector. note, some fuel will shoot from the line when you loosen it, be prepared to clean up some spilled fuel.John Kuderas/v Fifty-Fifty

 

[Steve O.]

governor

Could be a problem with the governor. Check the Yanmar tech manual or call the company before tackling this job.

 

[Paul Akers]

Try this...

...Disconnect the throttle cable at the engine and rev 'er up. See how many revs you get, then. It's possible that you have the wrong cable, or it's somehow "stopped" (governed).