A zongshen Appriya 300 could not be started. After receiving the car, I tried to start it, and found that the engine speed on the instrument was instantly displayed (about 300 RPM) and returned to zero. No matter how long the motor was running, it only showed the speed in the first 1-2 seconds.

First check the crankshaft position sensor signal! Following the engine magneto out of the line, we found that the cable connector was in the pedal position, and we could not measure the signal without disconnecting the pedal.

I'm done. I see the connector. The three output lines of the three-phase generator are fine. Put it aside. All that's left is a bunch of connectors, which must be crankshaft position sensors.

Look at the wire harness, the crankshaft position sensor should be 3 wire, and by rule of thumb, 3 wire must be hall type.

MSC super test lamp clamp battery negative, probe by wire test, damn! Not a bright one! Unplug the end of the wiring harness and found an orange line that could light up the test lamp. The multimeter measured and confirmed and found the battery voltage. The HALL power supply of 12V was found.

Insert the plug again and prepare to measure the signal. When the probe is inserted into the orange line, the test light does not turn on. Is the 12V power supply false connection? Or did the Hall sensor short-circuit and lower the voltage?

Disconnect the plug, use 3W power test lamp one end is connected to battery negative, the other end is connected to the orange wire cable end, the lamp can light up, but the luminosity is very weak, feel some strange, thinking how much electricity hall sensor can use ah? It should be enough! Rectify the fault of the virtual link.

But how do you measure the hall short-circuit pull voltage? Take the risk of dragging a wire from the positive end of the battery, leaving only a copper wire in the middle to connect (to act as a fuse), wrapping the other end around the probe and inserting the orange wire. Pop! The copper wire is blown. Hall shorted out. It burned. That's a loss!

Find magneto stator online. 360 yuan is pretty expensive. Bought immediately back to the car next to check, this suddenly realized, it is not the oil pressure switch! A white switch wire happens to be connected to the orange wire I tested earlier by a 3P plug. This crankshaft position sensor isn't Hall. It's magnetoelectric. What a mistake at grandma's house.

An idea flashed through my mind at this time. It was the words of the car owner. In fact, when the plug is disconnected, the customer inserted a mouth, the machine oil lamp does not show, at that time focused on measuring the signal, feel that the curve has no relationship with the machine oil lamp!

The next test went well, measuring the resistance of the crankshaft position sensor at 125 ω. Connect the plug, MSC super test lamp clip battery positive and negative, the probe is connected to the crankshaft position sensor output line, hit the motor test lamp flashing, indicating that the sensor is normal.

At this time, the instrument still does not show the speed, continue to let the owner of the electric start, my ear close to the oil tank to listen to the pump does not turn. There is a turn, indicating that the oil supply is basically no problem.

Check the high voltage circuit again, unplug the high voltage cap, remove the spark plug cover, hit the electric start, no fire, change a new spark plug, try again, spark is normal! Load to the car and then play, a start, instrument speed is also normal display! The problem was a broken spark plug!