What Causes an EFI Motorcycle with Fuel and Spark to Fail to Start?
2 Answers
An EFI motorcycle with fuel and spark failing to start is usually caused by insufficient cylinder pressure due to cold weather and degraded engine oil performance. Other reasons for a motorcycle failing to start are as follows: Fuel system faults: Mainly caused by fuel switch (no fuel flow), fuel filter (clogged), carburetor (no fuel flow or overly rich mixture), or bent fuel pipes. Electrical faults: Short circuits in electrical components (e.g., ignition switch, ignition coil, ignition module, or magneto failure) or open circuits caused by loose wiring harness connectors. Air pressure faults: Insufficient cylinder compression, improper air filter intake resistance, or engine intake/exhaust faults, etc.
My old EFI motorcycle had this exact issue before - fuel pump sounds normal, gasoline smell is present, spark plug shows perfect spark, but it just wouldn't start. After hours of troubleshooting, found out the crankshaft position sensor was dead - this component hides on the engine side, any dirt or improper gap will make it stop working immediately. Another time the ECU got waterlogged and kept throwing false trouble codes, but disconnecting the negative battery terminal for ten minutes miraculously revived it. Oh, and a clogged fuel filter can also cause insufficient fuel supply - don't be fooled by a full tank, the injectors might be starving. These kinds of failures are the most frustrating, you really need an OBD scanner to read trouble codes properly.
