My Yanmar will not start. The battery is fully charger. The fuel is clean. The glow plug lite comes on and then goes off. When the light goes off, I try to start it. The engine blows black smoke from the exhaust pipe. When I let the switch go, the engine stops immediately. I am puzzled. I removed the electric shut off and replaced it with a pull manual shut off. It's been working good after the replacement. One morning, I started the tractor, and moved it out side. I went back that afternoon, and no start , just black smoke..