Lets at least start with the basics. This way a low cost or no cost solution would appear.
Power to the ignition system
- When turning the key, does the starter at least go click?
- Is the fuse blown?
- Are the battery cables and posts CLEAN and TIGHT?
- Are the cable wires to the starter CLEAN and TIGHT?
- Your machine may have a solid-state VR. You would need a voltmeter to analysis if the power is being correctly regulated thru it.
- Check the back side of the ignition switch for loose terminals or arcing to ground.
Fuel side
- Are you able to see thru the fuel filter bowl? If so, is there any sludge at the bottom?
- How old is the fuel in the tank? Old fuel tends to go back with diesel eating microbes. Always use FRESH from a very active truck stop.
Air side
- Clean the air filter.
- Clean the radiator screen.