How I fixed a runaway L260 engine

I hate it when someone asks for help with a nagging problem and then doesn't let us know how it got resolved, so in the spirit of education, I offer this to my fellow L260 owners (and others!)

I thought I'd show how I (finally) fixed the sticking injector pump which caused my old L260 to "runaway" at near full throttle about a month ago.

The problem was a sticking fuel injector control rack which is part of the injector pump. This is the model injector pump used on my 1975 L260:



it is located right here in the RH side of the Z1300 engine:



The injector pump is integral with the governor (shown on the left side) and has a small inspection cover allowing access to the two pump plungers:



The governor and the pump each have their own oil sump and dipstick. the governor has a fill cap and a drain plug; the pump side appears to have neither (weird!?):



There is a sliding gear-toothed rack that slides side to side, turning the plunger adjusting pinions and adjusting the amount of fuel that is delivered with each stroke of the plunger. When the rack is all the way to the right, the plungers deliver maximum fuel (full throttle). My rack was sticking wide open on cold days and causing the motor to start and run at full throttle (very scary!) no amount of cleaning and lubricating in this area cured the problem:




Then I got an idea... notice the small cap or "can" on the left side of the pump casting. The rack extends out from the casting and into this "can" when at full throttle. Perhaps this "can" had moisture in it which froze on cold days and held the rack in WOT.



I went out one cold morning and opened the side cover. Sure enough, the rack was stuck in WOT position. I took a heat gun (i.e. a hair dryer) and applied heat to the "can" and in about 25 seconds the rack released and moved freely! EUREKA! it MUST be water in the can, but how to clean it out?

I stared at the can for a while and saw that it had two flats, so I put a 19mm wrench on it and gave it a tug - voila, she unscrewed and out dribbled about a teaspoon of water!



I thoroughly cleaned the end of the rack and dried and lubed it well:



I did the same with the can itself:




And now the problem is SOLVED. I have driven the tractor a few hours in cold rainy weather and started it in below freezing mornings and she seems to be fine!

I love the challenge of figuring out a problem and I am impressed with Kubota's engineering. To make this "can" easily removable is brilliant!

One question..should I fill the can with grease perhaps?

Anyhow I hopes this helps some other L260 owners!




Cheers,
Ren

Cavecreek, I used Adobe Photoshop, but there's got to be some free open-source software out there that will do it. I like the white lithium grease idea. I have some assembly lube I think I'll put in there, it is very non viscous.

Sheepfarmer, once you have the image looking how you want I t in Photoshop, go to ADJUST and set IMAGE SIZE so the longest dimension is 850 pixels. Then I choose SAVE FOR WEB AND DEVICES and save it with a new name.
At this point I upload it to Photobucket. When writing the post here on OTT, I have Photobucket open in a second browser window and as I'm writing if I want to insert the picture I go to Photobucket, display the picture and to the right of the picture I click on the URL link, that automatically copies the URL code for the pic. I then return to what I am writing and paste the URL code where I want the picture to appear in the text.
Preview the post before submitting to be sure the pics ended up as you wanted.

Coachgeo, duly noted. I will strive to change....I'm an old dog and these new tricks sometimes pose challenges.