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governor problem YM2500

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jameswms-HT

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Having problems with governor on my 2500.
Tractor runs great when cold ,but after it runs for a while with a load on it the governor starts to shut it down,you can increase the throttle and it will run a while longer untill you are at full throttle and it shuts down.
Let it cool for a while it will run again for a while then same thing..
I have checked everything else ,no cracked head,fuel injector pump rebuilt and also re checked,all fuel lines good and fuel is good and gets to the pump .Compression is 520 all cyls..
How can you check the governor and how hard is it to repair or replace..
 
I'm not sure that your engine has a governor. It has a throttle setting. How long does it run before it slows down? Sounds like a restriction somewhere. Did the symptoms (slow down) start gradually? If so, your fuel and air filters are where I would start.
 
I have replaced the fuel, the filter and bowl ,taken the muffler off,replaced the head gasket had the head checked,had the pump rebuilt ,had them recheck the pump,ran a leak down test and a compression check and yes it does have a governor.
The tractor runs for about 30 or 40 minutes then starts the slow down., I have checked all the simple things I am About ready to take it to Fedricks and tell them to fix or rebuild it.
 
Have you run it with the fuel cap loosened. In 7 years of following 4 or 5 Yanmar forums, I have never heard of a governor causing a problem; however, it shouldn't be that hard to inspect for proper operation.
 
I agree with Norm. Check the cap. If the cap is OK, pull the fuel line off of the pump the next time it dies. be sure you have a full steady stream of fuel to the pump. It sounds to me like a fuel starvation problem which is pretty common.

Common Causes:
Cap not venting,
Junk in the tank
Collapsed fuel line
broken fuel filter valve
clogged filter
etc

The only time I have heard of a governor problem is
1- a hydraulic pump shaft broke & the end got caught in the governor - freak accident
2- a person tries to pry their injection pump off without unhooking the internal linkages & breaks/stretches them.

In either case the symptoms were nothing like you described.
 
Norm in my 40 years of having a tractor I have never ran into anything that has stumped me as much as this thing has.
I can go outside right now and start the darn thing up and it will run like a top and operate just fine for about 30 or 40 minutes then start slowing down untill it stops. I agree with everyone ,that it some sort of fuel problem.
The heck of it is that you have to operate the tractor for over half an hour everytime you work on something to see if there is any improvement.
I have had it for 5 years and its been a good one but I'm ready to send it back to Japan in little pieces..lol
I used to bushog and when you hit some taller grass the governor would pick up engine speed when it started to bog a little but not it doesn't do that,you have to hit the throttle to keep it at the same rpm..
This is a problem that going to have to have the mechanic standing at the tractor and seeing whats going on ,Its hard enough to diagnose a small problem by someone just telling you what its doing,but this one is so far out in left field it crazyI am the type that hates to have something like this whip me but I thing this problem has gotten the best of me..
I appreciate the help from all who has tried to help,when I find out what the fix is I'll post it..
 
Aaron I think that when my son pulled the pump he didn't unhook the linkage and did mess up the governor,by prying or pulling on it ,because thats when all this started after the pump went out and was rebuilt..
 
"I can go outside right now and start the darn thing up and it will run like a top and operate just fine for about 30 or 40 minutes then start slowing down untill it stops."

That's about how long it takes to create enough vacuum to shut off the fuel if the tank is not vented.
 
I'd sure be sure here was a steady stream of fuel at the pump before I started down the governor path. The symptoms don't sound like the governor to me.

Governor problem symptoms are :
A)- start the tractor & it runs wide open & wont stop
B)- Tractor wont ever even start
C)- won't hold an idle (constantly goes up way & way down)
 
Did you figure this one out? <E>:?</E> Mine is doing the exact same thing. I have good fuel at the pump, I tried taking the fuel cap off. No luck. Has good clean fuel filter and air filter. Kinda acts like it runs out of fuel. Let it sit an hour or two, and it will start and run again for about 30 min. or so. Funny thing is it just happened overnight. One day I tilled with it for about 2 hrs, the next day I had this problem. ?????????
 
If you're saying you set the speed with the hand throttle, and that after a while it slows, the friction disc that lets the hand throttle resist the force of the return spring is surface-glazed and needs replacing. Meanwhile, tie the throttle to hold it where you want.
 
When your engine dies, pull the fuel supply line off that goes into the injection pump to be sure you have a good steady supply of fuel. If not- start backwards &amp; find a point where you DO have a good supply of fuel.
 
Does it smoke a lot before it dies? Try removing the muffler &amp; see if that fixes it. The Yanmar mufflers are notorious for coming apart &amp; blocking the exhaust passage. You get a lot of smoke as it slowly chokes out. Once it dies, the blockage falls to the bottom &amp;, once restarted, floats around until it plugs up again later.
 
I'm pleased to join this Forum; I think these discussions are extremely valuable, especially for weekend mechanics like me. I have a Yanmar 1500D and I have exactly the same problem that jameswms is experiencing. It runs for about 30 minutes until it heats up, then the governor has a mind of its own, and disregards any input from the throttle lever. I appreciate all the great suggestions posted, however in the end, it's definitely the governor. Has anyone undertaken replacement of the governor? I'm very apprehensive to tear into the engine to such an extent. I think I'll connect the throttle lever to the injection pump directly, thus bypassing the defective governor. Has anyone any comments or concerns to that approach? Many thanks to all.
 
I find the task daunting and overwhelming. I'm not a mechanic and I'm not certain I want to disassemble the front of the engine. Is there a simple and straightforward way to replace the governor? I would appreciate any advice or procedures if it's not as difficult as I'm assuming. Thanks.
 
The governor is not really a "thing" but a series of levers &amp; springs. You can't just get a new governor. You can get new springs &amp; levers but you will be right back where you are now. You need to tear into it with a service manual &amp; see what is wrong. Probably just a sticky pivot pin or sticky injection pump rack. Simple fix.

Attaching the throttle directly to the injection pump would be fatal to your engine &amp; it would not even be usable. The few minutes that you were actually able to keep the rpms steady enough to keep it from dying or exploding would require CONSTANT adjustment.
 
Thanks for the information Aaron. I was concerned about a direct connection from the throttle lever to the injection pump, and you confirmed it. A couple of other pieces of information: we can rule out a sticky injection pump rack; the pump is new and I've checked the rack recently again and it slides smoothly. The other observation (and this may be key) is that I can't kill the engine by pushing the throttle lever all the way off. The governor won't slide the injection pump rack all the way to the off position. When I remove the inspection plate, I can easily slide the rack to the far right position (off) with my finger but it doesn't stay there. There's a spring action pushing it back approx 3/8" away from far right end-of-travel position. Do these clues further indicate that the problem is what you're suggesting? If so, I'm still not comfortable with the prospect of tearing into the engine, so if anyone knows of someone in the Tucson area that is well-versed with these tractors, I would be highly appreciative knowing a place to bring it to for repair. Much thanks again.
 
If the rack slides smoothly it will probably be ok.

Did you ever adjust that screw on the front of the timing cover for any reason?
 
We have 3 guys here, compaining of governor problems, (which is almost unheard of). Pete, you say yours is the same as the others, (quits after 30-40 minutes, then you say gov. has a mind of it's own, (???), then you say you can't shut it off as the rack won't move fully to the off position. Is all of this correct? Except for the shutting off, if you have a foot throttle, possibly it is not fully restoring by it's spring tension, (a common problem).
 
Since Aaron mentioned that the Governor is not really a component, and that it might be gummed-up or sticky linkage; I got to thinking about my teenage years when I had a very old vehicle that I was trying to get running properly again. One of the first things I did was add an engine cleaner to the oil and ran it for a couple of hours. Then I drained the oil and replaced it with fresh oil. I'm considering doing this as my first step. Maybe this is all it'll take. Before I proceed, I wanted to post this idea to solicit any thoughts and comments; especially if there are any pitfalls or concerns. If none, I'll go ahead and report the results. Thanks again to all.
 
<QUOTE author="TucsonPete"><s>
</s>Hi Norm, so glad I'm not alone. Yes to all three symptoms. My tractor is doing all of them. But no, I don't have a foot throttle.<e>
Click to expand...
/e></QUOTE>

I just realized the other 2 guys problems were from last summer. I have to wonder if they really had governor problems.
 
Repairing a wonky problem with an oil additive to clean the engine? I'll put it this way. Engine shops might stock additives out front insofar as customers are willing to buy them, but not to use themselves on the shop floor as part of a repair process.
 
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