Yanmar 2QM15. engine lost power, then stopped

[Mychael]

I have an older engine in my boat but normally it runs fine apart from using a bit of oil. Usually an easy starter.

The other day after starting normally the motor failed and could not be re-started. We has been running for not more then five minutes.

The failure was gradual in that it just started slowing down as it would if you were closing the throttle.
There were no strange noises, no smoke or vibration.

Once the engine stopped it could not be restarted. So far I've established that fuel is available as far as the low pressure pump and that is supplying fuel to the injector pump.

Next step would be the injector pump or the injectors themselves but some ideas as to what might be the cause of the stoppage would be very much appreciated.

Mychael

[Landlubber]

Mychael, you are on the right track anyhow mate. Prove that the injectors are working is the next step.

I take it that you have loosened the fuel injector line at the injector to confirm that fuel is getting there, the next one is to pull an injector.

Sure it was not overheating at all....5 minutes with the seacock shut may nip her up?

[Mychael]

Originally Posted by Landlubber

Mychael, you are on the right track anyhow mate. Prove that the injectors are working is the next step.

I take it that you have loosened the fuel injector line at the injector to confirm that fuel is getting there, the next one is to pull an injector.

Sure it was not overheating at all....5 minutes with the seacock shut may nip her up?

Have not checked the injectors as yet, sure it wasn't overheat as I always look over the stern when I start to make sure I can see water coming out.
Also after we towed her back with my dinghy and it's 3.5hp motor (Oh the shame) we fiddled about for some time. Motor turned over freely and would have been well cool again then anyway.

I am currently thinking along the lines of fuel not being combustible. Although the filters were not blocked I had added a good dose of biocide into the tank, it may be that I made the dose too strong and effected the fuel itself.
I got a mate to put a fuel tap into a 20litre steel jerry can for me, I'm going to try some clean fuel to see what happens there.
I've currently removed the low pressure fuel pump as although it was pumping on the priming arm it was not a strong flow so I am going to either replace or overhaul that.
I've pulled the retaining caps off the injectors but so far have had no luck getting the injectors to release themselves from the block.

It's not lose of compression as there is still a huge difference when turning the motor over by hand-crank with and then without the de-compressor lever pulled in.

Mychael

[Landlubber]

Release the injector nuts a bit and turn the engine over with the starter, the injectors should lift off the seat.

[Mychael]

Tried turning over with the starter the other day. That also failed to loosen the injectors. I reckon they have been in place a long time, but thanks for the suggestion.

Mychael

[Landlubber]

well now you will just have to get a puller, make sure that you soak the threads and lower injector with Penetrene for a few days, or else use a gas torch to " warm" them up a bit.

[Mychael]

Originally Posted by Landlubber

well now you will just have to get a puller, make sure that you soak the threads and lower injector with Penetrene for a few days, or else use a gas torch to " warm" them up a bit.

Yes, fingers crossed. I've tried those pressure cans of shock cooling sprays. They would seem to be a total failure, wont bother to get them again.

I might see if I can obtain a puller, not too keen on flame in the confined area.

Already priced an injector overhaul, that will be around $120 per injector.
Still waiting on a price for either an overhaul kit or a new low pressure fuel pump.

Mychael

[kenJ]

Have you looked at the exhaust mixing elbow? A blockage there will cause the same problems. This is a very common problem on some older Yanmars, not sure which models.

[Mychael]

Originally Posted by kenJ

Have you looked at the exhaust mixing elbow? A blockage there will cause the same problems. This is a very common problem on some older Yanmars, not sure which models.

Have not checked specifically for that, although when I started the motor it was putting out fumes and water from the exhaust as per normal (before it stopped). The mixing elbow is only 2 yrs old.

Latest update,we got one injector out, the other we cannot budge.
The injector we removed we tested, bad pattern and in need of service but not the reason for the stoppage.
We've since brought the engine forward and are going to remove the head as there is no way the other injector is going to come out and we don't want to bust it.


Mychael

[Mychael]

Final update. Never actually found the reason for the stoppage but now have overhauled the head and fitted one brand new and one reconditioned injector.
Injector pump not touched, lift pump replaced although the old one was still working.
Engine now all back together and running fine although now not the easy starter it once was, that aside it now runs cleaner and with more power.

Mychael

[Mychael]

Update on engine.. After several hours of work now I took the boat back to have the motor re-checked.
The reason being that although the motor is running fine it went from being an easy engine to start prior to it's top overhaul to being much harder to get going on it's first start of the day.

Tappetts re-set, one was a bit loose the other a bit tight and the injector pump timing altered slightly (although that had not been touched before) so next time around I'll see if it's regained it's easy starting habits.

Mychael

[FAST FRED]

Fuel "conditioners" come in two styles.

One drops the water and contamination to the bottom of the tank, to be pumped out.

The other style mixes the gunk so the engine primary filter can catch it and be changed.

Sounds like the gunk was dropped and not pulled from the tank.

FF

[Mychael]

Here is another funny thing.. We manually drained the entire tank (had a a new tank made) what came out still smelled like diesel, felt like diesel but was a rusty red colour.
It was throwaway of course but before I did that I tried filtering it. I used a white cotton cloth spread over a device called a "Mr Funnel", an aviation funnel thing for separating water and contaminates from fuel it has it's own removable filter.

Anyway , emptied these cans of contaminated fuel through my double filter and almost nothing happened, the white cotton only slightly tinged red, there were no "big bits" of crap (like rust flakes, etc) being caught and after all the fuel had run through the funnel filter it was still the same rusty red and the filter caught,,,, nothing, no water, no contaminates.... weird.

Mychael

[brummie]

I had the same problem, engine slowly died, thought fuel was the problem but found it to be blocked mixer elbow.