04 Isuzu diesel truck will not shut off when key is off?

check engine shut off electronic valve on injector pump -most likely valve is stuck or fuse is blown -use a test light to check for power at the switch on the pump when key is turned on -to clean valve u need to remove the electrical wire with 8 spanner then undo solonoid valve located at the back top of the injector pump -usually a 25 or 27 mm. spanner will fit -make sure u dont loose the the poppet valve or spring and o ring when removing --when its out you can test on a 12v or 24 v depends on truck voltage - battery with live on pin and earth on frame of valve -valve should pull in when given power-