Fuel Return Line: Description and Operation

FUEL FILLER NECK

Fuel Filler:

To prevent accidental filling with other than unleaded fuel, vehicles that require unleaded fuel have a special filler tube. This filler tube has a restriction in it so that the only nozzles that can be inserted are the smaller diameter nozzles on pumps dispensing unleaded fuel.
It is recommended that the amount of fuel put in the tank when filling be limited to the automatic pump shutoff. Due to the expansion of fuel during temperature increases, or overfilling ("topping off") can cause fuel overflow at the filler cap when the vehicle is standing or the cap is removed.

FUEL LINES AND CONNECTORS

Hair Pin Clip:

Duck Bill Clip:

NYLON PUSH CONNECT FITTINGS
Nylon push connect fittings are designed with two different retaining clips. The "hairpin" clip is used on 5/16 inch (7.9mm) diameter tubing. The "duckbill" clip is used on 1/4 & 1/2 inch (6.35 & 12.7mm) diameter tubing.

Push Connect Fittings:

SPRING LOCK COUPLING
The spring lock coupling is a fuel line coupling held together by a garter spring inside a circular cage. When the coupling is connected together, the flared end of the female fitting slips behind the garter spring inside the cage of the male fitting. The garter spring and cage then prevent the flared end of the female fitting from pulling out of the cage. As a redundant locking feature, a horseshoe shaped retaining clip is incorporated to improve the retaining reliability of the spring lock.

FUEL TANK VAPOR ORIFICE AND ROLLOVER VALVE ASSEMBLY

Orifice Rollover Valve:

The fuel tank vapor orifice and rollover valve assembly use a small orifice and shutoff valve that allows only fuel vapor to pass into the line routed forward to the vapor storage canister. The rollover valve prevents fuel from flowing to the canister in the event of vehicle rollover.

FUEL CAP
The fuel cap is a threaded screw-on design and is secured to the vehicle with a tether. The fuel cap provides pressure and vacuum relief. Vacuum relief is provided after negative 0.50 psi and pressure relief above 1.8 psi. Under normal conditions the fill cap operates as a check valve, allowing air to enter the tank as gasoline is used, while preventing vapors from escaping the tank through the cap.