52Carl has given you a good working list. Go through them one at a time. Are you still 6 Volt? Then use BIG cables on the battery. Tractor supply places are good for those. Fuel in the oil? Drain, and fix the fuel pump. Fire is not your friend. Pull the plugs and look for wet(too much fuel in the intake). Wet plugs might be signs the needle is stuck in the carburetor. When set up properly these(inline 6 engines) start easy and run smooth and quiet.When the fuel issues are fixed we can talk tune up stuff.
