Runaway Yanmar-Help!

tjgator · Oct 16, 2006

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

Eddie · Oct 16, 2006

Did you know that the throttle works backwards on these tractors. Pull it backwards to go faster and push forward to slow down.

tjgator · Oct 16, 2006

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.

normde2001 · Oct 16, 2006

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?

HoyeTractor · Oct 16, 2006

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

kenmac · Oct 16, 2006

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,.

mark777 · Oct 16, 2006

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

tjgator · Oct 17, 2006

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

HoyeTractor · Oct 17, 2006

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

tjgator · Oct 17, 2006

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!!

HoyeTractor · Oct 17, 2006

The pump does come out of the top. You need to unhook the governor from the inside first. Just keep all of your shims (between the pump & block). As long as you use the same shims your timing should not change when you put it back. Be careful if you start taking things apart on the pump or you may need to get it recalibrated at a diesel injection shop.

Good luck,
Aaron
Parts@HoyeTractor.com
(940)592-0181

crb478 · Oct 18, 2006

I had the same thing happen with my 1720D after it sat for 3 years during a divorce settlement. It would start, but it ran wide open. I ended up taking the injection pump off and having it rebuilt locally, really just cleaned up. It has run great since then. That has been about 8 years ago now. It cost around 200.00 to have it rebuilt, but I believe it was worth it to assure that there are no future fuel problems down the road.

kenmac · Oct 18, 2006

glad to see you ended up with the tractor.

EFC · Oct 23, 2006

tjgator, after you pull the pump out don’t listen to that little voice in your head that says "I can fix this" take it to a diesel shop and have them go through it. There are a ton of parts in there as you can see and they have to be timed when put back together.

Buck

tjgator · Oct 25, 2006

Finally got around to removing the pump, at least I tried. I removed all lines and got them out of the way, as well as the 4 nuts that hold down the pump. Now I can only get the pump out slightly-not quiite enough to pass by the studs. I have removed the cover with 4 bolts on the side of the governor housing and can see where a slotted lever seems to have the pump captive. Can you help to explain how to get the pump the rest of the way out, before I get impatient and end up breaking something?
Thanks,
Tom

mark777 · Oct 25, 2006

Not sure which model you have but doesn't it have a water pump? And if so won't you need to remove it so the pump has clearance to come out fully?

Sorry....trying to help here.

Mark

tjgator · Oct 25, 2006

Well, I did get impatient and tried once more and it came right out. I guess I wasn't holding my mouth just right or got the right combo of @#$%#$@! cuss words. I did have to remove the exhaust manifold, but not the water pump. I got the pump out and the rack was frozen. I tapped it lightly once and it freed right up. I guess I'm just lucky. Tomorrow I'll put it back together and post an update. Thanks To ALL!!

roxynoodle · Oct 25, 2006

Good luck, I hope it all goes well for you.

tjgator · Oct 26, 2006

All did go well. I put it all back together this A.M. and other than a little trouble priming the engine It runs GREAT. This is a super place for info!
I followed the advice I got here and actually got it running. Price for all parts was $0.00. I spent more time before I found this site fooling around with it, trying to figure out the problem than I did in actually fixing it.

THANKS Again,
Tom