Yanmar YSM12

[John Conarroe]

My Yanmar has been sitting for 5-7 years. I had the head rebuilt new valves, guides, seats. It will kick over if I put oil in the intake ~1oz. but it only fires 4-5 times and won't kick again. I have tried Mystry Oil to free up the rings if that is the problem, no luck! I am trying to avoid pulling the piston but I guess I may have to. Any suggestions would be appreciated.

 

[Bob E.]

Fuel problem?

If it fires when you squirt oil into the intake, the piston rings and compression are probably OK. Are you sure you are getting good fuel flow to the injectors? There's a good book called "Troubleshooting Marine Diesels" by Peter Compton (see also www.boatdiesel.com) that is a good guide to identifying engine problems by subsystem. This book says you can take out the injectors, reconnect them to the high pressure fuels lines upside down, and visually evaluate the spray pattern. Might be worth a try before considering an expensive rebuild.Best of luck.

 

[berry]

fuel

have you nprimed pur in jectors because it sounds like your not getting fuel

 

[Paul Harmina]

Old fuel

I agree with Berry & Bob. It sounds like a fuel problem. If the fuel in your tank has been there for 5-7 years, it is probably contaminated or full of water. It is no wonder it will not support combustion.You need to darin the tank, clean it, and put in fresh fuel with a stabilizer additative. Worked for me. Also, make sure you add a good fuel seperator filter if you do not currently have one.