Fuel Tank: Description and Operation

FUEL TANK FILLER NECK
Expansion of fuel due to temperature increases, or overfilling ("topping off") could cause fuel overflow at the filler cap when the vehicle is standing or the cap is removed. To minimize this condition, it is recommended that the amount of fuel put in the tank when filling be limited to the automatic pump shutoff. If vehicle has two tanks, use fuel from both tanks after fill-up to reduce fuel levels.

PUSH CONNECT FITTINGS
Push connect fittings are used to make most fuel line connections in diesel fuel systems. There are two sizes for this vehicle 9.5 mm (3/8-inch) and 7.9 mm (5/16 inch).

Fuel Tank Selector Valve:

Fuel Tank Selector Valve Schematic:

FUEL SELECTOR VALVE - VEHICLES W/DUAL TANKS ONLY
The 6-port diesel fuel valve is powered by a small electric motor which opens and closes the valve ports. The supply and return ports for either tank open and close simultaneously. The valve is shifted to the front mode (that is the front supply and return ports open to the engine supply and engine return port respectively) by applying a positive 12 volts to terminal number 1. When the valve reaches the front mode position, an internal switch opens the circuit and stops the motor. Returning the valve to the rear mode is accomplished by reversing power: positive 12 volts to terminal number 1 and ground to terminal number 2. Terminals 3 to terminal 4, this supplies the front tank sender signal to the fuel gauge. Terminals 4 and 5 are connected to the in the rear tank mode. Therefore, a change in the fuel reading gauge (assuming at least 1/4 tank fuel level difference), means that the valve has shifted.