My boyfriend came across a kubota tractor he has already replaced the starter alternator and the regulator. It started yesterday ran good but now it won't start. It turns over like it wants to start. What could be wrong any suggestions
The tractor was produced between 1973 and 1976. Many tractors of that era did not die when the ignition switch was turned off. The throttle lever had to be moved to the cutoff position. To restart the throttle had to be moved from the stop position. If that isn't it the air path may be blocked or fuel flow may be blocked. Be sure fuel flows freely from tank, check fuel flow through filter, follow instructions to bleed fuel system.
And advise him to not use any starting fluid while trying to get it going. It could cause enough trouble internally he won't want to spent what it will take to fix it.
He needs to check the glow plug to see if they are getting power. He has to turn the key counter clockwise to get the glow plugs to get power. If they are working hold the key in that position for 15 seconds or so before turning clockwise to start.