Small Engines (Lawn Mowers, etc.): toro walk behind mower, connects 2, measure voltage

Question
Mower is a Toro Mod 3165 ser # 20989. Engine is Kawasaki 460. Problem: Blades do not engage. When I measure voltage at fuse output, reading is 17v. When I attempt to engage blades (activate clutch switch) voltage drops to 4v and blade does not engage. I have been mowing this summer by hooking up a car battery directly to the clutch. Clutch works fine. I am not sure how to determine what is wrong with the charging system on the engine. I also see a relay (bosch brand) that is involved in the blade engagement. I have cleaned the PTO ground (although didnt believe that to be the problem since it engages and holds with a car battery for power). I see the plug on the L side of the engine that connects 2 wires which seem to be coming from the charging coil. I cant seem to measure any voltage coming out of these 2 wires but do get 17v at the PTO fule on the output side of the fuse. As I stated, this voltage drops to 4v when I hit the momentary switch that energizes the PTO clutch. I have a VOM to trouble shoot. What do I do next?


Answer
Sounds like a bad ground to the regulator.  The wires you are talking about carry AC voltage. Test between the 2 and you should have 30+ volts AC.  If you don't have 30 the problem is the stator.  Is this an electric start engine with a battery. If not you probably need a new capacitor.