low RPM on Yanmar single cylinder

[Jeff Williams]

I have a 10GM Yanmar diesel on my 1984 25.5 and haven't been happy with the engine's operation from when I purchased the vessel nearly a year ago. I've had two mechanics work on it and replace various parts including, but not limited to, fuel pump, fuel injector, intake valve, to the tune of about $3k parts and labor. The engine would usually start okay and idle alright but then after leaving the dock it would often quit sooner or later. On advice from others, I have replaced the fuel line, added an external fuel filter/water separator as well as an electrical fuel pump. Now the engine hasn't quit for some time so maybe part of the problem has been fixed, but according to the book, I should be getting over 3000RPM's and usually can only manage around 2500 and sometimes not even that. Anyone have any experience with something like this or know what might be going on? Thanks

 

[Bill Murray]

prop size??

have you checked to see that you still have the correct size prop fitted? Did someone try to get more power by putting on an oversize prop??

 

[Ted]

Exhaust elbow

Does she also overheat or run a little hot? My understanding is that as the mixing elbow cokes up over time

 

[Joe M,]

Low Tech

I don't want to get your hopes up ---but --many times it is simply the throttle cable not adjusted properly.This is the weak link in the system since it is dependent on friction and can slip.Check it it's easy and cheap.Joe M.

 

[Anthony Bavuso]

clogged fuel filter

It sounds like you're already got this base covered but I have gotten the symptoms you have described twice on my 1GM and both times I replaced the fuel filter to solve the problem. I am sorry to hear that you are having so much trouble with your engine. I have had mine for a year or so and with some minor love and care the engine has really become dependable. I think the good news for you is that once you get the engine setup right and keep up on the maintenance that it will serve you well. It has been a good engine to me so far.