KUBOTA L2250 , 650 HRS, Starts, OK ,then jumps to full throttle with no key on/off effect). Replaced throttle STOP solenoid but the STOP lever is stuck[ in "full open". HELP!
If you have a solenoid on/off valve to shut off the engine, it should cut the fuel. If you have a manual fuel cut off make sure that it is connected to the control lever on the ejector pump.
Otherwise, either the metering valve is stuck full open or the governor's not working.
Jerry has the proper terminology had the metering valve stuck once and had the same result as you. I now use Stanadyne in the fuel for all my diesel engines for lubricity I'm sure there are many good products that will serve the purpose as well to help deter pump wear.