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Ilijanik 01-27-2013 10:21 AM

Yanmar 2gm20f
Hi everybody, I am a new sail boat owner. Just got Pearson 30 and I have problem with my yanmar 2gm20f engine. To make it easier to explain shortly, this is the list what I did and the probles:
I did:
Change the oil and oil filter. Now the oil level is 1/3 above minimum
Replaced old fuel with fresh diesel and replaced the fuel filter.
Put new battery
Air bleed the fuel system

What's happening:
The engine, hardly, but starts on key
Once starts, the engine runs on max rpm's with 0 throtle. The only way to stop the engine was to chock the air intake because the fuel shot off ( tried manually on the engine block) does not react.
Checked fuel delivery to the injectors and the fuel after high pressure pump is coming only to
the second injector, closer to the gear box, bot not to the first injector.
On the first start black smoke came from the exhaust, but after that no smoke or steam was coming out on max 3200 rpm's The sea water pump looks like is working good.
Any idea where I can start from? This is my first sail boat and first diesel engine to deal with. Thanks a lot!!!

HUGOSALT 01-27-2013 09:13 PM

Re: Yanmar 2gm20f
Welcome aboard, hopefully shortly you will agree, you have a good little engine there.
Was the motor running for the previous owner this past season
or was it not in operation for a period of time?
Did it run ok when run prior to purchase? or did you run it prior to purchase?
Does fuel shut off cable on the block not move, as in frozen, or does it move and still does not shut off?
Check the position of the compression release lever on 1st cylinder,
it should be in the same position as the 2nd cyl which is firing.
Do you have a service manual?(same for 2-3GM's) thinking you
should be able to download online?

Ilijanik 01-27-2013 09:36 PM

Re: Yanmar 2gm20f
The engine did not run on time of purchase. We did start only on WD40 not on the fuel was in the tank. I guess was an old fuel inside, that's why I did replaced it.
The both pressure levelers are in closed position. When I opened the #2 the engine stopes, same like when I loosed the fuel supply to the injector #2, the engine stopped again but not when I was playing with #1 pressure leveler and injector fuel supply.
I did not use any command from the helm, all operations were made on the engine block, the throttle end shutoff valve.
When the fuel supply tube was removed from high pressure pump to the injector #1, wasn't clogged,and after cranking the engine without putting the tube back, no fuel was coming from the high pressure pump.
Is it any chance to have fuel pressure for second but not for the first injector?
And is it any connection between throttle and shutoff not working with fuel supply on the first injector?

HUGOSALT 01-28-2013 12:31 AM

Re: Yanmar 2gm20f
Not a mech, so remember advise given is worth about what your paying for it.
"Is it any chance to have fuel pressure for second but not for the first injector?"
After making sure all fuel line fittings are tight and then adjusting your throttle governor screw (to reduce rpm's)I'm thinking could be
symptoms of troublesome injection pump.
Would sure be nice to find out some history of who last worked on
this motor, and what they did...maybe yard mech or previous owner?

hamburking 02-27-2013 12:50 PM

Re: Yanmar 2gm20f
My guess is that its simpler than you expect. Check the throttle idle set screw. I think the PO tried to get the engine to run by cranking the rpm so it wouldn't stall due to bad fuel. Now you have good fuel, and the low setting is way too high.

I have done this myself with outboards.

The yanmar is a great engine...and maybe its working perfectly?

chucklesR 02-27-2013 02:17 PM

Re: Yanmar 2gm20f
Engines running at wide open with no throttle can be oil foaming and what is known as a run away engine, but they produce large volumes of blue smoke.
I had that happen to me the first time I changed the oil in my 2gm20f (put too much in).
Actually, if you had that cloud on the first start, that may have been why, and then something broke while it was "running away".
Now you may have two problems, unrelated except for time.
First, you have a throttle problem. If while it was running away you were frantically jerking and pulling trying to shut it off it may have warped and or broken.
The throttle on a diesel is a complicated mess of stuff with governor springs, weights and fuel rack movement, injection limiters and such. You'll have to consult your manual, wiggle and pull on parts and see what is not moving that should move (or moving that shouldn't).

Second you have a blocked #1 port on your HP pump.
You can take your pump off and take it to a diesel shop to have them look at it. The bad news is that's expensive, the worse news is it's not something you can do yourself (true on most HP pumps).

Frankly, I'd recommend it's time to throw some dollars on it and have a qualified mechanic pick them off. This isn't a old lawn mower.

Ilijanik 02-28-2013 08:48 AM

Re: Yanmar 2gm20f
Suprising, the throttle sterted working by itself and now the engine is working great. I guess, this engine was neglected and the old fule staying inside made a lot of damage. The fule injector cleaner did the job, with a lot of playing with the throttle and the shot off valve. But now noticing another issue, the oil level is increasing. After oil and filter change, I left the oil level on half btw min and max and 10 working hours later, on higer throttle went to overspeed and had to chock the intake again. Checked the oil level, and now the level was little over maximum line on the stick and the oil was black. Repalced the oil and filter again but now I will monitor the oil level after every couple of hours of runing time. Any idea what could be the reason?

jsaronson 02-28-2013 08:59 AM

Re: Yanmar 2gm20f
fuel is getting into the oil, possibly due to a stuck ring on a piston. Not good news!

hamburking 02-28-2013 09:29 AM

Re: Yanmar 2gm20f
Don't panic!

It could be as simple as...the boat is sitting differently in the water. Did you move any heavy gear, fill a tank, or have another person aboard? It doesn't take much to change the oil level slightly due to the angle of the boat.

Otherwise, its either water or fuel. Wipe the dipstick on your fingers and give it a sniff for fuel. If you've got a water leak, you'll see "white smoke" in your exhaust.

However, its sounds like you've got it running again, and with all the stresses of the runaway throttle, it may have sorted itself out. A good remedy for many an old engine is simply a good 24 hour run...gets it fully up to temp, all the chunks can work themselves out, get the grease where it needs to be. Too often, marine engines get run for only 10 minutes at a time, and never get up to operating temps...this is hard on an engine.

I think you are doing the right things....keep changing the oil when its dirty, and keep checking the level. At some point, you might consider going for a sail...LOL!

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