Circuit Description

When ignition switch is first turned On, PCM energizes fuel pump relay which then applies power to in-tank fuel pump. Fuel pump relay will remain On as long as engine is running or cranking and PCM is receiving 58X crankshaft position pulses. If no 58X crankshaft position pulses are present, PCM de-energizes fuel pump relay within 2 seconds after ignition is turned On or engine is stopped. Fuel pump delivers fuel to fuel rail and injectors, then to fuel pressure regulator. Fuel pressure regulator controls fuel pressure by allowing excess fuel to be returned to fuel tank. With ignition on, fuel pump can be turned on by command from scan tool.