Yanmar 3cyl runs bad, governor?

[fdcg27]

We have a rear-engined Deere powered with a 3 cyl Yanmar diesel at work that's barely running.
The machine was in use when it suddenly started running really badly.
We suspect a governor problem.
Does anyone here have any experience with these engines?
Also, does anyone know of a good source for Yanmar diesel parts?

 

[suspiciousmind]

How many hours on the unit?

I have that engine on my Deere lawn tractor with 420 hours and have had no problems at all.

I'd be sure all filters, air and fuel, are clean before I'd look at anything else. My first guess is it's starving for one or the other.

 

[Bgallagher]

Originally Posted By: suspiciousmind
How many hours on the unit?

I have that engine on my Deere lawn tractor with 420 hours and have had no problems at all.

I'd be sure all filters, air and fuel, are clean before I'd look at anything else. My first guess is it's starving for one or the other.


+1 Check the basics and replace if necessary. Have you ever run a cleaner through the fuel? It might be gummed up. Also, do you winterize the tractor? If you didn't drain it then the fuel might have gummed up.

 

[JTK]

It's hard to say off-hand what it could be. Fuel pump problem maybe? Yanmar diesels typically last forever. Deere has used them for decades.

 

[fdcg27]

This particular Yanmar has been in use for seventeen years.
It has more than 4K hours on the meter.
It is used to cut grass during the season and to push snow during the winter.
We suspect a governor problem because calling for more power (I know that's an akward construction, but I hate to use the term "throtle" with a diesel) has zero effect.
The thing will barely idle, and if you advance the power lever, nothing happens, and yes, it is moving the lever connected to the governor.
The engine ran fine right up until the point that it didn't, and we're confident that the lift pump and filters are fine.

 

[AVB]

Check all the fuel lines it could be sucking air. The braid on those hoses is good at hiding leaks. Is it running rough or just not reving? If it is running rough you most likely have a fuel issue. If the govenor was bad it should still run smooth. Have you tried cracking the lines at the injectors to see if you are getting fuel?

 

[AVB]

I think I had a bad return like cause that on one of those mowers before.

 

[JTK]

If I remember right, there's a bunch of shims and small bits associated with injector timing on the fuel pumps for the 3-cyl JD Yanmars. Valve seating issues is also not uncommon for one with 4000hrs, but you'd think the issues would come on slow.

Did this problem happen all at once?

Joel

 

[fdcg27]

Yes.
The thing ran just fine until it suddenly barely ran at all.
The reason that we suspect the governor is that moving the power lever has no effect at all.

 

[OVERKILL]

Originally Posted By: fdcg27
Yes.
The thing ran just fine until it suddenly barely ran at all.
The reason that we suspect the governor is that moving the power lever has no effect at all.


Sounds like you guys have it pretty well narrowed down.

BTW, those Yanmar's are great engines, we had them in the Deere tractors at the park, and they ran like clocks.

 

[doitmyself]

It sounds like you ruled out fuel supply issues. But, I had your symptoms on a Yanmar powered JD compact tractor. The fuel outlet was on the bottom of the fuel tank. A quarter sized piece of tree leaf got into the tank and clogged that outlet hole. It was a very frustrating diagnostic process. Sometimes the leaf would dislodge enough to allow operation, then it would plug up again.

Please follow up with your outcome.

 

[fdcg27]

Based upon all of the above, I'll get our tech to look again for any obstructions to the fuel supply as well as any possible air leaks.
If we find nothing there, I think we'll go ahead and replace the injection pump/governor assembly.
One of the nice things about a fully mechanical diesel is that there are not too many things which can go wrong.
I'll be sure to post the outcome here.

 

[fdcg27]

Since you asked, I shall.
The tech and I both ended up feeling pretty foolish.
Our tech called the Deere dealer to price a new or rebuilt injection pump. I don't remember the exact cost, but it was pricey.
Anyway, we buy a lot of parts from this dealer, so they know us and are willing to offer helpful advice.
The parts guy suggested from what our tech told him that someone had put gas in the fuel tank.
Now, the users swore that they hadn't put gas in the tank, nor could you smell any gas in the fuel, although the scent of diesel would likely overwhelm that of gasoline.
Anyway, our tech drained the fuel and put in fresh diesel.
After it worked through the residual of the old presumably gasoline contaminated fuel, the thing ran like a champ again.
Just goes to show you that it's often something simple causing a problem.
Had the users told the truth, and said that they had accidentally added gasoline to the fuel tank, the issue could have been resolved quickly and easily.
That's okay, since I know who was supervising the operation of the equipment on that day.
They don't have a whole lot coming from me or the tech for the foreseeable future.

 

[Donald]

Originally Posted By: Bgallagher
Originally Posted By: suspiciousmind
How many hours on the unit?

I have that engine on my Deere lawn tractor with 420 hours and have had no problems at all.

I'd be sure all filters, air and fuel, are clean before I'd look at anything else. My first guess is it's starving for one or the other.


+1 Check the basics and replace if necessary. Have you ever run a cleaner through the fuel? It might be gummed up. Also, do you winterize the tractor? If you didn't drain it then the fuel might have gummed up.


Its a diesel so I do not think draining the fuel is needed.

 

[fdcg27]

I think you're right.
Anyway, you can't just drain a diesel as you might a gas system.
You want fuel in the injection pump at all times to protect its very finely machined surfaces operating at very close clearances from corrosion.
Even if the pump suffers no harm, who would want to bleed the thing to get it running every spring?

 

[doitmyself]

Originally Posted By: fdcg27
Since you asked, I shall........

Just goes to show you that it's often something simple causing a problem.


Thanks for the "rest of the story"! I can't tell you how many times I have put on "blinders" and made a wrong assumption based on symptoms. I try EXTRA hard now to consider all the possibilities. It ruffles my feathers when I finally break down and take something to a mechanic or trades person only to find out it a "blown fuse" or some other stupid simple thing I overlooked. But, I am getting a tiny bit better in my golden years.

You're problem would have been very tough to figure out and that is why the really good mechanics (and parts guys)are keepers. You should buy him a box of doughnuts. Some dealers would have had you bring it in and rake you over the coals, even knowing that a simple solution might be possible. Kudos to that parts guy for suggesting a cure. This type of service that was common place years ago is getting rare.

 

[fdcg27]

That's also why it pays to find a good parts source and use that dealer exclusively.
If they get to know you and you're a steady customer, they're more inclined to give you helpful advice.
The other side of that is that you're more likely to remain a loyal customer, rather than trying to save a couple of dollars on any given part.

 

[JTK]

LOL! Thank for the update on that one fdg27. Some gas in there probably didn't hurt a thing on the old girl. Dilute what you cant suck out of the tank with diesel and go with it.

Back around 1989-1990 I worked for a large rental vehicle company and I recall several times people putting gasoline in the diesel powered cube vans. They'd run, but run terribly and shoot flames out the tailpipe.

Joel