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gilligansail · 16-08-2010, 15:42

Hi,

I have a Yanmar 2QM15 that stalls out on occasion. It seems to be at random
times. When it happens it slows down as if someone hit the throttle lever and
then dies. I can usually restart it after waiting a few minutes. Sometimes it
will only run at idle or low RPM after these episodes.

What I have done so far. Replaced fuel lines from tank to engine. Replaced
fuel filters. Had mechanic check primary and secondary fuel pumps. Had
injectors tested and one replaced.

One mechanic who worked on it said the cooling system inside the engine was
really corroded and he thought the cooling system was failing due to being
clogged. and the engine was stalling due to over heating. It did seem like
that was the issue once, as the engine stalled and seemed very hot.

The last stall-out just happened this weekend after motoring for about 2 hours
on a river. The engine didn't seem that hot to me. I could put my finger on
the head for a few seconds without getting burned. And water was still coming
out the exhaust.

I've owned the boat for 5 years, had multiple mechanics look at it and no one
has solved the problem.

Can you help?

Tropic Cat · 16-08-2010, 15:48

Sounds like the fuel pickup in the fuel tank is clogged. When the debris floats away the engine runs normal until it sucks the debris in again.

DeepFrz · 16-08-2010, 15:52

Or the tank vent is clogged. Is there a wire screen on your pickup tube? If there is, get rid of it.

Chief Engineer · 16-08-2010, 17:53

Old Engine, Old Fuel tank, clogged exhaust elbow

Mark Zarley · 16-08-2010, 19:15

The weaning down of an eng (a gradual loss of power) is usually a filter issue. Since you have replaced all the filters and lines to the tank. You need to go one step further and get at that suction tube. The eng restarts in a few min without bleeding which indicates the fuel pump has a vacume problem. Supply line is plugged, or the vent could be plugged .

**Ex-Calif** · 16-08-2010, 19:46

- Any black smoke, blue smoke, white smoke or steam from the exhaust?

- Is it correlated to any particular loading of the boat. i.e. heavier loading against currents or heavier than normal boat or towing something?

- I wouldn't discount a cooling issue completely

Chief Engineer · 16-08-2010, 21:19

That's why diesel are so different....They give you symptoms...like a human.

gilligansail · 18-08-2010, 21:15

My plan is to polish the fuel. Sound good?

The vent works fine. How would I know if the exhaust elbow is the issue?

chief engineer, yes sometimes blue and black smoke. Does seem to happen at higher rpm after longer running times.

Arch Stanton · 18-08-2010, 21:43

I have the same engine and recently digitized my (non-copyrighted) service manual.

If you'd like a copy, drop me a line and I'll send you a link to the 20MB .PDF