Yanmar 2GM-F hard start/rough running

[DaveLaneNS]

My 2GM just started acting up (oh the shame to be towed home by one of the boats who beat me in a race!) last night. Before this it has been very reliable having not failed me (in this and the previous season that we've owned it).

After our post-race raft up, I started it up normally, set the revs to about 2000 for some warm up, then in less than a minute it quit. It has never done that. It took a lot of cracking and fiddling to get it started. It would usually start, but stop within a few seconds. The times that it would stay running, it was running roughly (varying rpm) with not much power.

The race itself was quite bumpy and at high heel angle. The only other symptom I have it the previous week on the way home the throttle had to be held up to get the rpms over about 2200 but when you held it up the power was there to get the rpms up. I thought that was fixed with some WD40 on the cable mechanism at the engine end.

Does this sound like a fuel issue or maybe something in the governor?

--- Dave

[DrB]

It sounds like:

1. Dirty fuel
2. Air In The Line

Usually when a diesel idles or runs rough it is because of dirty fuel or trace air. Try changing your fuel filters and fully bleeding the air out and see if that helps. If that doesn't help, it could be that the injectors need to be cleaned. If after you change the filters and bleed the air, you're still getting it, look for palces where air could be leaking in such as crushed o-ring, loose bleed screws and clamps, etc.

Also, why do you start your motor and immediately set it to 2000 rpm to "warm up"? I start my motor, let it idle, then ramp up. I can tell when the motor is sufficiently warm to ramp up or put under a small load when the vibrations reduce and there is a perceptive "pitch" change in the sound. On a 70 deg F day, this may take a minute or so.

DrB

[wwilson]

Dave,

I second DrB's diagnosis.

Air in the fuel line will sometimes act like a fouled filter, but the engine will cycle up and down in RPM. Dirty fuel will clog the filter(s) and pretty much limit higher RPMs.

Your mention of a bumpy race, of course, makes one think of tank sediment loosened and clogged filters. But, using the, "try the easiest & cheapest fix first" method, I recommend bleeding the fuel line first (crack the #1 injector for a few seconds while the engine runs & retighten it while still running). If that has no effect, replace the fuel filter(s) - and bleed the line again afterward.

Wayne

[chucklesR]

Checking the condition of your fuel filter via a simple eyeball check is probably the easiest check, might as well change it while you are at it tho. A Air filter check is also called for.

[DaveLaneNS]

Thanks for the advise guys. I'll give this a try the soon as Hurricane Bill blows by!

Normally I don't run the engine at hi-rev to warm up, but this time we were in the middle of a raft up of many boats and the noise is a good hint that were about to "break" loose the outside boats that they better get ready! I usually just start and go as soon as other things are ready.

--- Dave

[timebandit]

First apply rule #1.

If that does not apply then I would check the condition and tightness of anything dealing with the fuel from the tank to the the lift pump, cracked hose, loose clamps or fittings.

[LakePirate]

You might check the tank to make sure the gauge is working properly. I had a similar thing happen to me a couple months ago. My 2GMF has always run great. Then on the way back to the marina it started loosing power and sputtering, in a matter of less than a minute and half it died. The gauge showed 1/4 tank. After filling it up and bleeding the lines it runs great again.

[badsanta]

-No fuel
-dirty fuel= clogged filter
-a slipped throttle cable, so even if the throttle is wide open the control may have slipped at the engine so nothing moves.
-the stop handle is partial pulled

[badsanta]

Please post your fix. I would like to know how it went. Thanks

[DaveLaneNS]

I drained the Racor filter (there was some sediment, but no water noticed), I bled the fuel lines up to the port on the engine-mounted fuel filter, then at the two injectors and afterwards, it started and ran fine for a short drive. Before doing this, it would not stay running and was hard to get it to "catch".

I still need to get out and give it a good run and check to see if the throttle issue is still there.

I did not have the tool needed to replace the engine fuel filter so will do that at next opportunity and bleed it again. I also replaced the air filter while I was at it. All the lines from the fuel tank look remarkably new so much have been replaced not that long ago (this is my second season with the boat).

I'll post again when I know more.