[SpudRider]

DIAGNOSING TYPICAL ENGINE PROBLEMS

Insufficient Fuel Supply

Turn the engine off for 15 seconds. Turn on the ignition, and listen for the fuel pump to build pressure in the fuel system.

Remove the fuel injector from the throttle body, and press the starter button. The injector should spray fuel.

Turn off the ignition. Connect a fuel pressure meter to the fuel pump. Turn on the ignition. The meter should read a fuel pressure of 36 psi. If the pressure deviates more than 3 psi, either high or low, replace the fuel pump.

Ignition Problems

Disconnect the wiring plug from the fuel injector. Pull the spark plug wire, and verify spark from the plug wire to the spark plug.

Engine Stalling While Decelerating

Check the battery voltage. Check electrical connections to the MAP/MAT sensor, idle stepper motor, and throttle position sensor. Verify the emission canister purge valve is functioning correctly. Check both of the purge valve hoses for leaks. Check the intake manifold and throttle body for air leaks.

Connect the EFI scan tool/computer, and check for diagnostic trouble codes (DTC).

Check the valve lash.

Clean the throttle body and idle stepper motor with brake cleaner. Clean the MAP/MAT sensor.

Poor Acceleration

Check the fuel filter. If the fuel filter is blocked, replace it.

Turn off the ignition. Connect a fuel pressure meter to the fuel pump. Turn on the ignition. The meter should read a fuel pressure of 36 psi. If the pressure deviates more than 3 psi, replace the fuel pump.

Verify the exhaust system is not blocked.

Clean the MAP/MAT sensor, and check its electrical connector.

Connect the EFI scan tool/computer, and check for diagnostic trouble codes (DTC).
Check the throttle position sensor (0-100 values) and its electrical connector.
Check the O2 Voltage while the engine is idling (100mv – 800mv values), and the electrical connector for the oxygen sensor.

If either sensor is bad, replace the sensor.

Poor Fuel Mileage

Connect the EFI scan tool/computer, and check for diagnostic trouble codes (DTC).
Check the throttle position sensor (0-100 values) and its electrical connector.
Check the O2 Voltage while the engine is idling (100mv – 800mv values), and the electrical connector for the oxygen sensor.

Check the coolant temperature sensor, and the MAP/MAT sensor.

If any sensor is bad, replace the sensor.

Check the fuel injector system for leaks.

Check the emissions carbon canister for blockage, and check the canister purge valve.

Inspect, and clean the air filter. Check the valve lash.

Difficulty Starting the Engine

Inspect the valve lash.

Check the fuel filter. If the fuel filter is blocked, replace it.

Turn off the ignition. Connect a fuel pressure meter to the fuel pump. Turn on the ignition. The meter should read a fuel pressure of 36 psi. If the pressure deviates more than 3 psi, replace the fuel pump.

Clean the fuel injector.

Disconnect the wiring plug from the fuel injector. Pull the spark plug wire, and verify spark from the plug wire to the spark plug. In necessary, change the spark plug.

Clean the throttle valve body with brake cleaner.

High Idle Speed, High RPMS While Shifting or Disengaging Clutch

Connect the EFI scan tool/computer, and check for diagnostic trouble codes (DTC).

Inspect the throttle body and throttle cable.

Electrical System Problems

Check the battery voltage (12.5 V) and connections.

Turn on the ignition key, and verify the fuel pump is operating.

If the electrical system is not activated, check the ignition switch, engine kill switch, and clutch safety switch.

Check all electrical connections and fuses.

Note: Whenever checking for sufficient spark, always disconnect the electrical connector from the fuel injector. Always turn off the ignition before removing any parts from the electrical system.