1. Fault phenomenon of electromagnetic switch not responding. Turn on the ignition switch to the start gear, and the electromagnetic switch does not respond. Cause of fault: The attraction coil is broken, the holding coil is broken, and the contact disc is burned. The contact thickness is insufficient. Fault inspection and elimination. Under normal circumstances, when the ignition switch is placed in the start gear, you should be able to hear a "click" sound from the electromagnetic switch, and then the drive gear will mesh with the flywheel gear ring. If there is no such phenomenon, it is a fault of the electromagnetic switch. Remove the electromagnetic switch and disassemble it for inspection. If the joint of the attraction coil or the joint of the holding coil is broken, use an electric soldering iron to weld the joint. In the absence of an electric soldering iron, you can first clean the wire end of the holding coil iron terminal, and then press it on the end cover of the electromagnetic switch and tighten the end cover screws. If the above conditions are good, check whether the contact disc is severely burned. If it is severely burned, use sandpaper of No. 1, or turn it over for use. If the contact thickness is insufficient and cannot be less than millimeters or it is severely burned, it should be replaced. 

2. Fault phenomenon of starter not turning. When the ignition switch is turned on to the start position, the electromagnetic switch "click" sound can be heard, but the starter does not rotate. 1. Cause of the fault Armature winding grounding, short circuit or open circuit Field winding grounding, short circuit or open circuit Starter armature shaft bending or bearing too tight, loose, and armature scouring. Fault inspection and elimination. If the armature winding is short-circuited and grounded, a multimeter is required to find the fault location. In case of such a fault, the part should generally be replaced. Open circuit faults rarely occur, because the armature winding wire is thicker and it is not easy to break the circuit inside. It is often caused by the wire head falling off or the wire being thrown out. Grounding and open circuit of the field winding are the most common, because the current passing through the starter during starting is quite large. Once grounded or used improperly, the wire head is easy to burn. If it is desoldered or generally broken, it can be used after welding. If it is burned and broken, it must be replaced. Short circuit faults rarely occur, and parts must be replaced in case of such faults. If the armature shaft is bent, the bearing is too tight or the armature is scouring, the cause should be found out and replaced with a new part. 

3. Fault phenomenon of weak starter rotation. The starter rotates slowly and weakly, and the engine is difficult to start. Cause of the fault: The gap between the front and rear copper sleeves is too large or the armature shaft is bent. The grounding brush between the commutator and the brush holder end cover is too worn or the spring tension is too small. Fault inspection and elimination. During the starting process of the starter, if the gap between the front and rear copper sleeves is too large, whether it is the front or the rear, the armature will come into contact with the magnetic field due to radial swing, causing a short circuit or a bore sweep, thereby affecting the normal operation of the starter, increasing the resistance to the starter rotation, and causing difficulty in starting. Therefore, when replacing the copper sleeve, a new graphite bronze sleeve should be used, and it should be reamed according to the standard. The matching clearance between the armature shaft and the copper sleeve should be one millimeter. The grounding of the commutator and the brush holder is mainly caused by excessive wear of the rear end cover gasket or loose adjustment nut of the front end cover, which causes the armature to move forward and backward. In addition, it is also necessary to check whether the brushes are unevenly worn and whether the brush spring tension is too small.