C 1500 Truck 2WD V8-6.5L DSL Turbo VIN F (1998)
Fuel Pump Control Unit: Description and Operation
FUEL BALANCE CONTROL SYSTEM
The fuel balance control system consists of the following components:
- Front (main) fuel tank sender.
- Rear (auxiliary) fuel tank sender.
- Balance fuel pump.
- Balance fuel pump relay.
- Fuel sender and balance module.
On vehicles with dual tanks, the front tank is the main and the rear tank is the auxiliary. The main fuel pump supplies fuel to the fuel injection unit. The
low pressure (about 32 kPa or 7 psi) fuel balance pump is used only to transfer fuel from the auxiliary tank to the main tank in order to balance the fuel
levels in both tanks. As the main tank level drops to about 25 % below the level in the auxiliary tank, the fuel sender and balance module energizes the
fuel pump relay. This pumps the fuel from the auxiliary tank to the main tank. When the level in the main tank reaches a level slightly higher than the
level in the auxiliary tank, or the auxiliary tank is empty, the module de-energizes the balance pump relay and fuel pump. Any malfunction in either of
the fuel gage circuits will disable the system and the fuel will not be transferred from the main fuel tank to the auxiliary fuel tank.
FUEL PUMP BALANCE MODULE
The Fuel Pump Balance Module relies on input from the primary and secondary fuel senders, and cannot operate if the fuel gauge is not working
properly.
For Fuel Pump Balance Module testing and inspection refer to Instrument Panel, Gauges and Warning Indicators / Symptom Releated Diagnostic
Procedures / Fuel Gauge See: Instrument Panel, Gauges and Warning Indicators/Testing and Inspection/Symptom Related Diagnostic Procedures
For Fuel Pump Balance Module electrical diagrams refer to Instrument Panel, Gauges and Warning Indicators / Diagrams / Electrical. See: Instrument
Panel, Gauges and Warning Indicators/Diagrams
