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Re: Yanmar 4GM Shift question
I would remove all the fuel from the tank and clean the tank, change all filters, and then add all new fuel with a biocide and a fuel injector cleaner and lubricator. Not sure of your tank access, but really need to see what is in your tank after pumping all the existing fuel out. To make this easier, try contacting a local fuel polishing company (one recommneded by a good boat yard or other boaters). They may be able to filter and reuse your fuel, or dispose of it legally if it is no good. Most of the fuel biocides and injector additives seem to work although some boaters swear by them and others say they are a waste of money. If used per directed they should at least cause no harm.
I think you shifting problem could be fixed with proper adjustment of the shiter, shifter cable (might need lubrication), and cable connection at the transmission. Also check if engine vibration is in some way causing the transmission shift linkage to "shift" the transmission- maybe a loose transmission/engine mount.
Last edited by casey1999; 02-19-2013 at 07:50 PM.