Yanmar 2GM20F starting woes.......

[CLP]

I'd really appreciate the views of learned forum members on recent problems staring my Yanmar. I'll be as brief as possible but the tale so far is:

The engine was installed in 1998 and has performed without trouble until this season.
It's total running hours is around 2300 hours.
I've maintained it throughout as per the Manual.
This season, getting it to fire from cold, has progressively become more difficult. Air seemed to be the problem and the engine fired up after a minute or two spent bleeding the fuel line. Once running the engine performed fine and would start ok if restarted within about 6 to 12 hours of stopping.
I cleaned out the tank and fuel lines, checked fuel line connections, replaced filters, washers etc and put new fuel in but this didn't improve things.
A month ago things got harder and the engine refused to fire at all.
The yard's engineer got it going but only by using Easy Start and when cold, the problem returned.
I left the yard to investigate further.
They checked the fuel lines, tested the injectors, cleaned out the exhaust, tested compression and found low compression in one cylinder.
The head came off and the head gasket was found to be blown, so that's been replaced and everything put back together BUT...
The engine still won't fire.
So the yard are now scratching their heads too.
Does anyone have any ideas???
Many thanks

 

[pete]

It's a long shot but similar happened on a 1GM10 I use to have, it suddenly developed a starting problem after being laid up over winter.
When it was cold it had to be cranked over for ages before it would fire (no white smoke out of the exhaust) but once started would run fine and restart okay until the next cold start.
We tried all the usual easy checks without any luck and for some reason decided to remove the injection pump and have it checked out. With the pump removed we could obviously see nothing wrong with it but I stuck my finger in the hole left by the pump and felt a spring loaded lever, when I touched it it sprung back (like it was stuck and the spring could not return it) once it was free it sprung back nicely every time ! We replaced the pump immediately and the engine was back to normal.
We decided it must be a fuel enrichment device to help starting, linked to the governor.
I then found that on my 1GM10 this lever can be reached with a finger through the oil filler hole without removing the pump. But obviously not on a 2GM20F
Pete

 

[RichardS]

I'd really appreciate the views of learned forum members on recent problems staring my Yanmar. I'll be as brief as possible but the tale so far is:

The engine was installed in 1998 and has performed without trouble until this season.
It's total running hours is around 2300 hours.
I've maintained it throughout as per the Manual.
This season, getting it to fire from cold, has progressively become more difficult. Air seemed to be the problem and the engine fired up after a minute or two spent bleeding the fuel line. Once running the engine performed fine and would start ok if restarted within about 6 to 12 hours of stopping.
I cleaned out the tank and fuel lines, checked fuel line connections, replaced filters, washers etc and put new fuel in but this didn't improve things.
A month ago things got harder and the engine refused to fire at all.
The yard's engineer got it going but only by using Easy Start and when cold, the problem returned.
I left the yard to investigate further.
They checked the fuel lines, tested the injectors, cleaned out the exhaust, tested compression and found low compression in one cylinder.
The head came off and the head gasket was found to be blown, so that's been replaced and everything put back together BUT...
The engine still won't fire.
So the yard are now scratching their heads too.
Does anyone have any ideas???
Many thanks

Does the engine still start with Easy Start or is even that not working now?

If it still starts with Easy Start then it has to be a fuel problem. Have the yard turned the engine over with an injector out or started it and then cracked open the injectors in turn to see if the running alters.

If all the lines are clear of air when you bleed through to the injectors but it still only starts with Easy Start and had good compression then I can only think that there is something wrong with the injection pump as suggested by Pete. I don't know what this lever is that he's referring to but can you find it on an engine diagram and see if it's stuck?

If it now doesn't start with the Easy Start but the compression is good then it sounds like an air problem ..... blocked air filter or something but this would really test the limits of my experience as an engine (diesel or petrol) with a fuelling problem which doesn't at least fire with a bit of fuel thrown in the intake is very unusual.

Richard

 

[pete]

I found this on the net for a 1GM10 I guess the 2GM20 is similar.

View attachment 54247

Pete

 

[garvellachs]

I'd really appreciate the views of learned forum members on recent problems staring my Yanmar. I'll be as brief as possible but the tale so far is:

The engine was installed in 1998 and has performed without trouble until this season.
It's total running hours is around 2300 hours.
I've maintained it throughout as per the Manual.
This season, getting it to fire from cold, has progressively become more difficult. Air seemed to be the problem and the engine fired up after a minute or two spent bleeding the fuel line. Once running the engine performed fine and would start ok if restarted within about 6 to 12 hours of stopping.
I cleaned out the tank and fuel lines, checked fuel line connections, replaced filters, washers etc and put new fuel in but this didn't improve things.
A month ago things got harder and the engine refused to fire at all.
The yard's engineer got it going but only by using Easy Start and when cold, the problem returned.
I left the yard to investigate further.
They checked the fuel lines, tested the injectors, cleaned out the exhaust, tested compression and found low compression in one cylinder.
The head came off and the head gasket was found to be blown, so that's been replaced and everything put back together BUT...
The engine still won't fire.
So the yard are now scratching their heads too.
Does anyone have any ideas???
Many thanks

This sounds like a leak in the fuel line to me - because it started after being bled. Any small fuel puddles anywhere on the engine side of the fuel pump? Have you any reason to wonder about the fuel line joints on the tank side of the fuel pump? I would check everywhere - tightening all the joints slightly. These engines suffer eventually from leaks in the bleed screws on the engine fuel filter body - we had to buy a new one to cure it.

 

[CLP]

Thanks for the responses.

There haven't been any fuel leaks that I can think of and the fuel lines have been checked and double checked.

I don't know if Easy Start is still needed to get it going, I'll need to check with the yard after the weekend. The word back after the head was put back on was that it wouldn't fire at all, so I assume even Easy Start isn't working.

The injector pump might be faulty although there is fuel at the injectors.

The other possibility is that the timing has somehow gone wrong, although I can't see how that might have happened

It's all very mysterious, and potentially expensive!

Any more suggestions gratefully received.

 

[RichardS]

Thanks for the responses.

There haven't been any fuel leaks that I can think of and the fuel lines have been checked and double checked.

I don't know if Easy Start is still needed to get it going, I'll need to check with the yard after the weekend. The word back after the head was put back on was that it wouldn't fire at all, so I assume even Easy Start isn't working.

The injector pump might be faulty although there is fuel at the injectors.

The other possibility is that the timing has somehow gone wrong, although I can't see how that might have happened

It's all very mysterious, and potentially expensive!

Any more suggestions gratefully received.

The yard need to check the compression again. If the engine won't fire (not necessarily run) with Easy Start then I suspect the yard have screwed up the valve timing or lift really badly. Not that easy to do but some of the work I've seen by auto and marine engineers (actually witnessed in the case of the latter until I stopped them) would make you cringe! :ambivalence:

Richard

 

[earlybird]

Suggestions;
Has compression been checked with new head gasket? (Not as easy on "F" model with no starting handle).
Valves could have been leaking in addition to gasket failure. Presumably the clearances have been checked, better still re-ground while the head was off.
AFAIK, there is no fuel enrichment device on a GM, but the fuel rack might stick.
If fuel is being fed to the injectors some suspicion is removed from the pump, is any injection sound audible, again easier with a handle, but a wooden stick used as a stethoscope might help.

 

[Tammany]

Are the exhaust valves & seat corroded?? Had same issues on 1gm10 and a replacement valve seat & new valve sorted it. Local engine shop sorted the valve seat for £50. Starts easily now.

 

[garvellachs]

When cold they are meant to be started on full throttle - something happens to help on that setting. Sometimes they start on one cylinder only, then the other comes to life soon after. So the problem seems to affect both cylinders? What was the secondary filter like when you changed it? Your talk of changing the fuel etc makes me wonder whether water has got into the injection pump and rusted up? When you bleed the injectors (crack the pipes loose) is there a healthy flow of diesel there?

 

[nemodreams]

I found this on the net for a 1GM10 I guess the 2GM20 is similar.

View attachment 54247

Pete

My drawing - well modified yanmar drawing. The link to the page that describes how a 1gm10 governor works ( how I sorted out it worked anyway ) is below .

I should add - looking at this drawing again ( will edit it sometime ) that the fuel rail K is attached to the base of the injector pump. With the injector pump removed K would not be there. The pin on the fuel rail K has to engage the slot L when re-fitting the pump.

They are very misunderstod things !

http://www.lena.geoffrichings.co.uk/sail_site/governor.html

 

[CLP]

Again, thanks for the suggestions, all appreciated.

The fuel flow at the injectors was fine. I changed the fuel when I changed the filters and checked the fuel lines. The filters were clean, no sign of muck or water. Changing the fuel seemed like a good idea at the time as I'd emptied the tank to clean that anyway. There was some muck and water in the bottom of the tank, so cleaning that was a job done not before time. I was convinced at that time that it was either a leaky fuel line (because I was having to bleed the system to get the engine to fire) or failing that, a dirty fuel problem, neither of which now seem to be the issue.

I'll be checking with the yard if they've rechecked the compression after refitting the head.