Fuel Gauge Sender: Description and Operation
Fuel Tank And Hoses:
Fuel Pump Module Exploded View:
OPERATION
The modular fuel sender assembly mounts to the threaded opening of the plastic fuel tank with a multi-lipped seal and threaded retainer (nut). The spring loaded reservoir, containing the exterior inlet strainer, electric fuel pump, pump strainer and reservoir replenishing jet pump, maintains contact with the tank bottom.
This design provides:
^ Optimum fuel level in the integral fuel reservoir during all fuel tank levels and driving conditions.
^ Improved tank fuel level measuring accuracy.
^ Improved coarse straining and added pump inlet filtering.
^ More extensive internal fuel pump isolation for noiseless operation.
^ Addition of service drain port and exterior nylon pipe with plugged connector, to allow draining of fuel from fuel tank.
The modular fuel sender assembly maintains optimum fuel level in the reservoir (bucket). Fuel entering the reservoir (bucket) is drawn in by:
^ The jet pump, through the external strainer
AND/OR
^ The secondary umbrella valve,
OR
^ The return fuel pipe, whenever the level of fuel is below the top of the reservoir,
PUMP OPERATION
The high pressure roller vane fuel pump used in this system is part of the fuel sender assembly. The fuel pump connector assembly prevents the transmission of vibration and noise generated by the pump to the fuel tank, Fuel enters the lower inlet port of the electric fuel pump after being filtered by the fuel strainers, as seen in figure. The initial function of the pump is vapor separation. The first stage separates vapor from the fuel in the pump. This vapor separation maximizes hot fuel handling and permits the vapor to return to the fuel tank at lower pressure and temperature. By creating positive fuel pressure, the pump then discharges the liquid fuel into the roller vane section of the pump. Attached to the pump outlet is a diverter which allows the primary fuel volume to flow into the convoluted fuel pipe, but also delivers a portion of the flow to the jet pump.
FUEL FLOW
The primary fuel flow proceeds through the convoluted fuel tube into a check valve. The check valve seat is molded inside the connector body. The check valve body and retainer are assembled into the connector body. The check valve restricts fuel back flow.
After the check valve, the fuel exits the assembly through the fuel feed output fitting on the molded cover. The cover also contains a fuel return provision which connects to one of three hollow support pipes.
CONSTRUCTION
The modular design adds additional functions that improve accuracy and ensure constant, steady fuel supply under all conditions. All components and subassemblies of the modular sender attach to a common cover and access the fuel tank through a single opening.
The modular fuel sender assembly is spring loaded to the bottom of the fuel tank. This "bottom referencing" permits continuous fuel pickup and accurate fuel level sensing.
The reservoir assembly is the lower section of the modular unit which encases both the roller vane pump and the jet pump. A retainer attaches to the top of the reservoir. Fuel is captured and maintained in reservoir at a level sufficient to submerge the rollervane pump.
A rubber bumper (pad) is assembled between the bottom of the reservoir and the fuel sender strainer, This promotes noise isolation by acting as a buffer between the reservoir bottom and the fuel tank and provides a fastening mechanism for the fuel level sensor assembly to the reservoir and the drain hose to the bottom of the fuel tank.
QUICK CONNECT FITTINGS
Three quick connect pipe end fittings are molded onto the cover of the modular unit for ease of unit removal from the fuel tank. These quick connect end fittings allow fuel feed, fuel return, and drain functions.