Runaway Yanmar-Help!

   / Runaway Yanmar-Help! #1  

tjgator

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Oct 12, 2006
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11
I just got this tractor and have little experience with Yanmars. It has a 3 cyl engine, #3T72HA. It has not been run in 2 years. I drained the fuel tank, changed fuel filter, charged the battery,and tried to start it. It finally started after a bit of coaxing, but has no speed control. The linkage seems OK-it all moves all the way to the injector pump, and the arm on the pump also moves. The engine just revs and revs, until I slow it down with the comp release, and finally that's how I have to stop it. I took off the cover on the injector pump and looked inside and see a couple of parts moving when moving the shaft. I need help to figure out how to control the speed of this engine. THANKS
 
   / Runaway Yanmar-Help! #2  
Did you know that the throttle works backwards on these tractors. Pull it backwards to go faster and push forward to slow down.
 
   / Runaway Yanmar-Help!
  • Thread Starter
#3  
It doesn't matter which way I push the lever, and I had actually removed the llinkage from the injector pump to the dash lever to make sure it was moving at the pump and moved the pump lever by hand.
 
   / Runaway Yanmar-Help! #4  
Strange problem, I'm surprised you got it started at all without bleeding the air from the fuel lines. I would try that, also, does it have a foot throttle? if so, does manually lifting the foot throttle help at all?
 
   / Runaway Yanmar-Help! #5  
It has not been run in 2 years.

Was it running when it was parked or did you buy it that way? Sounds like a governor issue to me. That "running away" is usually what happens when someone tries to remove the injection pump without unhooking the governor linkage first. The governor on those engines is really a very fragile mechanism. When you move the throttle lever on the pump you are really only "asking" the governor to give you more fuel by applying pressure to it's linkages. The governor is actually what controls the throttle.

Aaron
Parts@HoyeTractor.com
(940)592-0181
 
   / Runaway Yanmar-Help! #6  
If you know the person you got it from, I would ask if he/ she had anyone working on the tractor .If so, what was done , was it doing this when it was parked, was it parked because of this , etc,.
 
   / Runaway Yanmar-Help! #7  
tjgator,

IMO the pin on the control rack is not centered on the governor lever...

I had an identical experience where I missed centering the pin while removing and replacing a pump on a 1610D. Even with the inspection cover off, moving the reconnected throttle linkage and watching with a flash light, it looked installed correctly. What I was seeing was the governor lever sliding back and forth correctly...but the rack pin was buried behind the yoke (and stayed there) creating wide open throttle.

If the (fuel lines, waterpump and) injector pump has been removed and replaced I would repeat the entire procedure to be absolutely sure the rack pin is centered to the governor yoke.

Mark
 
   / Runaway Yanmar-Help!
  • Thread Starter
#8  
I did bleed the fuel lines as well as change the fuel filter before starting. There WAS water in the fuel system from the leaking fuel cap. According to the previous owner(who GAVE it to me)it was running before it was left to sit for a couple of years. The reason he quit using it was because it had battery/starter problems and when he shut it off he just left it in the field.
Where is the governor rack and how do I get to it? I don't have a manual yet.
Thanks,
Tom
 
   / Runaway Yanmar-Help! #9  
Where is the governor rack and how do I get to it?

If it had water in the fuel and it and has not been apart before it is likely that the rack stuck open. If they get water in the fuel they get rusty and bind. To see the rack clearly you will need to remove the injection pump. Sometimes you can oil it up and get it to work again.

this is what the governor looks like-->

GOVERNOR: Yanmar Tractor Parts

This is what is inside your pump-->

INJECTION_PUMP: Yanmar Tractor Parts

#4 is the rack. It unscrews #10 to vary how much the pump piston moves and how much fuel is delivered in each stroke.

Aaron
Parts@HoyeTractor.com
(940)592-0181
 
   / Runaway Yanmar-Help!
  • Thread Starter
#10  
To Hoye tractor: that is what I was looking for! Thanks, I'll give it a try. If I am correct the injector pump comes out through the top where the three injector lines are? Is there a secret to reinstalling all this as far as timing goes or do I just put it back in? I will definitely be dealing with you for parts when the time arrives. It's nice to have a knowledgeable source when buying parts for the DIY market that doesn't treat you as if you are just a PITA (pain in the *****).
THANKS!!
 
 
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