Yanmar 3HM35F Issues

[bfharris]

Hello all.

I have a sailboat with a Yanmar 3HM35F. This past Sunday we were making our way across the bay and approaching the channel to head into the marina. We fired up the diesel and it started like always. It warmed up, then we proceeded for about 10 minutes at 2500 RPM, when it suddenly decelerated to 1000 RPM. I pulled back on the throttle and she died. She acted like air had entered the system, so I bled her, but no air.

We had a friend tow us in. At the dock I bled the system again, with no luck. There is plenty of fuel flow to the injector pump, but taking the high pressure lines off and placing a napkin on top, it only wets the napkin and doesn't blow it off like I would expect. So I suspect the fuel injection pump has gone bad, but there is no leaking of fuel into the crankcase or outside. I figured I'd pull the pump off per the manual to take it to a shop, but after removing the low and high side lines, plus the 4 nuts that hold it on, it wouldn't come off, so I wonder if I missed something.

Also, just turning the diesel over a few seconds will emit a smell that almost smells like burning plastic around wires, but there is no evidence of anything burning (smell comes from engine compartment).

The diesel has always put out some steam, but not much and it dissipates after a foot or two behind the boat. Sunday there was a little more steam than normal, but not much and it we had just had a cold front come through, so I figured the cooler air had something to do with the additional steam, cause every winter it always steams more than in the summer.

The coolant level is the same and there is no water in the oil or oil in the coolant, so I don't think I blew a head gasket.

I perform all of my maintenance and always try to make any repairs myself, because I want to understand the diesel, so if something happens while I'm away from dock, then I can fix it, but I'm at a loss and would rather not call a mechanic if I can help it. Does it sound like the injector pump? If so, how should I proceed on removal?

I greatly appreciate any and all assistance. This boat is my home and I really enjoy changing my backyard whenever I want, so the thought of not being able to leave a dock bothers me.

Ben

[bfharris]

Update: I pulled the injectors. Two look clean and normal, but one is silver on the end and appears melted. Any idea what would cause that?

[Blues harp]

I would guess the injector was not sealing after injecting fuel and combustion was returning to the return line.... it has happened before.

[bfharris]

Thanks. I suspected that, but hadn't seen the end of an injector look like this before. I'll take them and the injection pump to a fuel injection shop for rebuild tomorrow. Hopefully that will get me back in business.

[westwinds]

Water?