SRX AWD V8-4.6L VIN A (2004)
Fuel Pump Relay: Description and Operation
FUEL PUMP RELAY
The fuel pump relay allows the ECM to energize the fuel pump. The ECM enables the fuel pump whenever the crankshaft position (CKP) sensor pulses
are detected.
The function of the fuel and air control system is to manage the fuel and the air delivery to each cylinder, optimizing the performance and the driveability
of the engine under all driving conditions. The fuel sender allows retrieval of fuel from the tank and also provides information on the fuel level. An
electric fuel pump contained in the modular fuel sender pumps the fuel through the nylon lines and an in-line fuel filter to the fuel rail. The pump is
designed to provide the fuel at a pressure above the regulated pressure which is needed by the injectors. The fuel is then distributed through the fuel rail
to six injectors inside of the intake manifold. The fuel pressure is controlled by a pressure regulator that is mounted on the fuel rail. The fuel system in
this vehicle is recirculating. This means that any excess fuel that is not injected into the cylinders is sent back to the fuel tank by a separate nylon line.
This removes any air and any vapors from the fuel as well as keeping the fuel cool during hot weather operation. Each fuel injector is located directly
above each cylinders two intake valves. The throttle body regulates the air flow from the air cleaner into the intake manifold, which then distributes this
air to each cylinders two intake valves.
Unleaded fuel must be used with all of the gasoline engines for a proper emission control system operation. Using unleaded fuel will also minimize any
spark plug fouling and extend the engine oil life. Leaded fuel can damage the emission control system, and use of leaded fuel can result in loss of
emission warranty coverage.
