My Cat 257B won't start. I am getting no fuel to the cylinders. The unit went down last week and I have just replaced the shut off solenoid. It started and ran fine after the new solenoid was installed for about 10 minutes. I brought it into the yard and raised the bucket up while I added fuel. While I was adding fuel the engine died and now it is just like before with no smoke coming out of the exhaust. I have fuel at the filter. Is it possible the ignition switch is faulty and not sending voltage to the solenoid to keep the piston retracted? Any thoughts on what is happening? It has a new alternator, fully charged battery. With the bucket raised the hydraulic level is not showing, is there a safety switch which kills the engine if hydraulic fluid gets too low?