Simply replacing components cannot solve the problems in the electronic fuel injection system maintenance

Before 2019, motorcycle repair could be regarded as a technical job. However, with the development of manufacturing technology and the transformation of market demand, motorcycle repair has shifted from mainly relying on technical repair to mainly replacing parts.

In the early days, motorcycles were luxury items for ordinary people, and the supply of spare parts was not sufficient. When a malfunction occurred, it mainly relied on repairs. Things like repairing carburetors, grinding valve seats, and boring cylinders were common.

After the implementation of the National IV emission standards for motorcycles, the maintenance technology of the electronic fuel injection system has become increasingly important. If a maintenance technician knows nothing about the electronic fuel injection system, they won't even know where to start when it comes to replacing parts.

Take a maintenance case as an example:

Recently, a customer sought help. The vehicle has been in use for two years. In recent times, the vehicle has been experiencing occasional automatic stalling, and there seems to be no pattern. Once the fault occurs, the only option is to wait for a while, and then it can be started again. Sometimes, it may operate normally for a day or two.

The maintenance station master asked the customer whether the vehicle's fault light would come on when a fault occurred. The customer said it wouldn't, or it would stay on constantly and then go out once the vehicle was started. (Normally, the fault light stays on before the engine is started and will automatically go out 2 - 3 seconds after the engine starts running.)

According to the user's description, this is not a directly manifested fault. Such faults are the most difficult to accurately diagnose. This customer has asked two nearby repair shops, and both said they couldn't repair it because they didn't have a fault diagnostic device. It is recommended that the customer come directly to the service station for repair.

When encountering such a malfunction, it is no longer like before. The maintenance worker used to replace things one by one and could always fix it.

First of all, it can be analyzed that this fault is definitely not with the sensor, because a sensor fault would trigger a malfunction indicator light. According to the user's description, this vehicle does not show a malfunction indicator light. So, it can be inferred that the probability of an actuator fault is relatively high.

The maintenance station master connected the fault diagnostic instrument to the OBD plug, turned on the ignition switch, detected a fault code, and the display showed an injector fault.

After cleaning the fuel injector and the plug, connecting them properly and clearing the fault code, the fault was not eliminated.

Therefore, check if the power connection is loose, as looseness may cause similar malfunctions. When checking the power connector, it was found that one of the secondary wires on the positive pole had been crushed. However, it was not completely broken, and there were still several copper wires connected, which had rusted, resulting in intermittent poor contact and thus causing the malfunction. After reconnecting the wires, the malfunction disappeared.

Thus, it can be seen that a rather simple fault can make the performance of the electronic fuel injection system quite confusing. To repair the electronic fuel injection system, one must have a good understanding of its principles, circuits, and fault phenomena in order to repair it smoothly. Simply replacing components can no longer solve the problem.