I have already replaced the vapor solenoid you are speaking of after the place it was purchased from many years ago diagnosed that for $450... and wanted $1100 additional to replace. And the tech boogered the wires with regular meter probes instead of piercing probes... I did replace it with a brand new one for much less, but the vapor solenoid is not bad, it is not getting the PWM voltage, I tested next to my neighbors fully operational FG15HT-20, theirs gets a PWM signal during cranking and at idle, but does not get it for initial key on like some have said..


RPM sensor - I have changed both the cam and crank rpm sensors.
Thermostat? do you mean temp sensor? I guess a faulty temp sensor could tell the engine not to give fuel... I can check that.

Next steps:
1 - hook a PWM injector pulse tester to the vapor solenoid and see if it passes fuel, it should, it may even start and run a bit
2 - trace the vapor solenoid power and ground wire to the ECM and verify not a bad connection


Since mine is a 2007 model, I believe it does not have the separate LP controller, and that function is built into the PCM, but a replacement PCM is $2000. I would send mine in for repair, but I have a funny feeling about all the places promising to fix for $4-600..

For a $2000 new part, I think I will pay to have a Komatsu authorized repair center replace it and make sure they give me back my old part and I can try to have it fixed for a spare...