We've got a Thomas 2200. I'ts got a 4 cyl Kubota. On the injector pump, there's a small knob on the back end of the pump. It rotates about 1 turn and was set about 1/2 turn. Just wondering what it is?
Does it have a hose come off of it and go to the fuel return rail at the injectors?
It sure does
Sounds like an air purge valve typical to Kubota engines. Not sure how it works on a Kubota in a Thomas, but on Bobcat Machines that use them, they have a primer bulb in the fuel line. When you change the fuel filter on them, you open the valve (knob) CCW until it stops, pump the primer bulb, and purge the air from the injection pump. Once air is purged, close valve CW until it stops, engine is now ready to run.
I checked the manual and they have a very lousy picture pointing to the bleed screw which looks like it might be in the same place. Really hard to see. I turned it counter clockwise and pumped the primer pump (plunger on top of filter housing) and nothing came out. Didn't use much force though on the "knob".
Hmm. Does it go into the return line?
It typically does on Kubota engines. If the injection pump is full of fuel, the primer pump would be firm even with bleed valve open. It's when there is air in the supply line, like when you change the filter, that the bleeder valve allows air to purge from injection pump until it's full of fuel, then primer pump would feel firm again. That's when you close the valve for normal engine operation.
Thanks Atco, that explains it.
No problem grasshopper.