Stator

Stator

The stator is comprised of two separate winding systems. One is a typical 3-phase alternator used in a variety of motor vehicles. The other is a single-phase alternator devoted to powering the fuel pump.

There is an error in the TR280i Wiring Diagram. The block marked “PICK UP” on the wiring diagram shows 4 wires that go directly into the ECU. Under the alternator cover is a 2-wire variable-reluctance pickup that senses trigger teeth on the perimeter of the flywheel. The resistance between the pickup coil wires (red and white) measures about 177 ohms.

The other two wires (red/black, white/black) are from the single-phase alternator that powers the fuel pump via the ECU. This is the same method used in some Arctic Cat snowmobiles that employ a Kokusan Denki ECU. The resistance between these two wires is about 0.85 ohms. Although the fuel pump “runs” when a 12-volt battery is connected to the system, it does not produce its full-rated pressure.

The fuel pump stator winding produces about 11.5 VAC RMS (loaded) at idle. This is about +/-15 V peaks, comprising 7 positive-going pulses followed by 7 negative-going pulses. See oscilloscope trace.

With a battery connected in place of the capacitor, you can hear the fuel pump run for a few seconds. The fuel pump can also be heard when the crankshaft has rotated only a small amount as when you re-position the kickstart lever to get a good full kick. I am guessing the ECU is using these other stator coils, at least partially, to sense the small movements of the flywheel.

The wiring diagram block marked “VOLANTE MAGNETICO” translates into “flywheel” and has 3 wires. This is a typical 3-phase permanent-magnet alternator. It is connected to a standard rectifier/regulator that produces the approximately 14-volt DC output required to charge a lead-acid battery (if one were present).

The resistance between any two gray wires is about 0.6 ohms.

Assuming 12 o'clock is zero degrees, going counterclockwise, coils are located as follows:

Six big coils are centered at 0, 30, 60, 90, 120, and 150 degrees (estimated).

Nine smaller coils are centered at 180, 200, 220, 240, 260, 280, 300, 320, and 340 degrees (estimated)