Close call when engine quit

[alexco38]

Went out on Saturday for a sail and overnight stay over with family. As we left the harbor, the Volvo 2002 Raw water cooled diesel start loosing power. That's strange because I maintain the engine meticulously every year. Oil, Filter and impeller changes, winterize and all. We've done over 100 engine hours this year so far with no hint of any problem.

Turning back to the bay, the engine loose power to a point that it quit. I can re-start it but loose power when put in gear. I couldn't get her into the narrow entrance and getting close to the rock. Just circle around a few time and really getting too close to the rock. No good as the light wind is blowing towards the rock. I couldn't sail around as the sails were not up yet. Even too close to drop anchor.

Luckily a friend sailing nearby and got a tow back into the club.

After a cold beer to calm down, I changed the engine fuel filter, bleed the fuel and the engine fired up right-a-way. So the fuel pump is ok. Put into gear and ran up to 2500 rpm tied to the dock for 20 minutes. No problem at all. There is no air leak into the system as I repeated the start and ran in gear two more time with no problem.

Went home and cut open the old filter. It was very very clean. Now I am lost.

Slept over it and tried to form a possible reason. I am thinking of a theory that may make sense. What if the vent is clogged. The fuel may not be able to be drawn out due to vacuum.

I am going to try to blow out the vent line tonight and see if there is any thing inside. I don't know why the vent would be clogged as there is a screen on the outside.

Have anyone experience similar situation? Any other recommendations and thoughts?

 

[FastOlson]

FWIW.....Similar experience -- Slowly lost power, faltered, then stopped and would not restart.
Each time we found a miniscule vacuum leak in the Racor filter that was letting small amounts of air sneak in until the injection pump caught a large enough bubble to stop it.

Each time it was the older (late 80's) Racor with the multiple plastic plugs and the plastic priming pump in the top, and also a plug in the bottom. Over time, some of these threaded fittings can start to pass some air. Tightening them a skosh did the job in the short term, and replacing the whole filter assembly came next. I went to a newer model - R20 - and my buddy changed to a 500 series. With 20-20 hindsight I should have also changed to the 500. Filters would be a lot less expensive, too.

So, look for a leak in an old fuel hose and check the lift pump, etc. But be extra suspicious of any possible leaks on the vacuum side. They only show up as a slow drip or a damp place with a drop of diesel, once you've shut down for while.

On the whole, I love diesels for their simplicity, but..... when folks rattle off the old mantra that "all they need is fuel, fuel, and fuel.... wow are they right!

 

[Don12364]

AFTER you changed the filter presumably you bled the system.
Maybe just bleeding was all it needed.
Also you must have re-made the seal round the filter. Perhaps an air leak there was the cause?

Is your Volvo self bleeding like most of the modern Yanmars? If not either of the above might be the answer.

A clogged vent would most likely have collapsed the walls of the fuel tank inwards before it stopped the engine.

 

[alexco38]

Good point about the vacuum. It did not deformed the tank wall. I'll check anyway.

I do have one of those older Racor with a hand pump on top as FastOlson said. I'll replace it just to be sure.

I changed those filters and bleed the system last year (fall haul out). Since then, the engine has over 100 hours this year with no problem.

The volvo is self bleeding but the engine mounted filter is not. I have to push a small lever and bleed air through the screw.

 

[fox islander]

On my C30 (M25XP) I found that if I overfill the tank some fuel enters the vent line and sits in a low spot. Found this out blowing on the line...shot some diesel overboard. Luckily no epa. Now I only fill the tank till the gauge reads full.