Evening everyone, ive got a ford 1620 tractor. Ran it one weekend all day no problem. Following weekend jumped in and no start and the whole harness caught fire. I repaired the harness and still no start. The engine is loosing its ground when starting because the glowplugs are getting power when cranking. I replaced the glowplug timer relay and its still live. This machine does have a preheat which is working. All glow plugs are good. Any help would be appreciated