FUEL LINES (carries fuel between the tank, the
pump, and other parts)
An automotive fuel tank must safely hold an
adequate supply of fuel for prolonged engine operation.
The location of the fuel tank (fig. 4-2) should be in an
area that is protected from flying debris, shielded from
collision damage, and one that is not subject to
bottoming. A fuel tank can be located just about
anywhere in the vehicle that meets these requirements.
Figure 4-3 shows the general construction of a fuel
tank used on automotive equipment. Fuel tanks are
usually made of thin sheet metal or plastic. The main
body of a metal tank is made by soldering or welding
two formed pieces of sheet metal together. Other parts
(filer neck, fuel tank cap, and baffles) are added to the
form to complete the fuel tank assembly. A lead-tin
alloy is normally plated to the sheet metal to prevent the
tank from rusting.
The fuel tank filler neck is an extension on the tank
for filling the tank with fuel. The filler cap fits on the
end of the filler neck. The neck extends from the tank
through the body of the vehicle. A flexible hose is
normally used as part of the filler neck to allow for tank
vibration without breakage.
In vehicles requiring unleaded fuel, a fuel neck
restrictor is used inside the filler neck. This prevents the
accidental use of leaded gasoline in an engine designed
for unleaded. The restrictor is too small to accept the
larger leaded fuel type pump nozzle.
If the restrictor is removed and leaded fuel
is used in a vehicle designed for unleaded fuel,
the catalytic converter will be damaged. This
action is a violation of federal law; therefore,
NEVER remove the filler neck restrictor.
Modern fuel tank caps are sealed to prevent escape
of fuel and fuel vapors (emissions) from the tank. The
cap has pressure and vacuum valves that only open
under abnormal conditions of high pressure or vacuum.
Figure 4-3.Fuel tank with top cut away.
Figure 4-2.Common fuel tank locations.