Yanmar YM2000 Injector pump pumping fuel regardless of position of throttle

jrdeming · Jun 22, 2014

While diagnosing what I thought was a fuel problem on my YM2000, I removed the inner workings of the injection pump (a major mistake as I've come to realize). I found and fixed the real problem, which was a bad ground and bushings worn out on the starter and was able to get the tractor fired up.

Unfortunately at that point, the engine revved beyond the redline and did not respond to reducing the throttle. I had to shut the fuel supply off on the fuel filter.

Removing the delivery tube from the injector pump while turning it over, I am seeing fuel pump when the throttle is fully turned off. I have been unable to find information in the service manual for reassembling the injector pump properly. There are yellow and red marker lines on the gears but I don't know how they should line up.

I have a friend that is very mechanically inclined and has worked on many types of engines but didn't know how these should be lined up.

Any help would be greatly appreciated.

Thanks

Fireman 9731 · Jun 26, 2014

Sounds like the internal governor may be damaged or out of adjustment. I'd say its time to remove the pump and send it to a professional shop or buy a new one. I would try here: Japanese Tractor Repair Dixon, IL

Indirocz28 · Sep 10, 2018

Unfortunately I don’t have anything to say on helping your over rev issue, but I was curious if you’d mind describing a little better what your symptoms were in the beginning and where/what you found at the starter and how everything was acting?

I am having some hard starting issues with my YM2000 as well, and sure seeming like a fuel problem, but I would sure like to double check on mine what you found on yours.

Thank you, and good luck!