Description - Fuel Delivery System; Operation - Fuel Delivery System; Diagnosis And Testing - Fuel Pressure Leak Down Test - Dodge 2001 Ram 1500 Owner's Manual

14 - 2 FUEL DELIVERY - GASOLINE
FUEL DELIVERY - GASOLINE

DESCRIPTION - FUEL DELIVERY SYSTEM

The fuel delivery system consists of:
• the fuel pump module containing the electric
fuel pump, fuel filter/fuel pressure regulator, rollover
valve (certain modules), fuel gauge sending unit (fuel
level sensor) and a separate fuel filter located at bot-
tom of pump module
• fuel tubes/lines/hoses
• quick-connect fittings
• fuel injector rail
• fuel injectors
• fuel tank
• fuel tank filler/vent tube assembly
• fuel tank filler tube cap
• accelerator pedal
• throttle cable

OPERATION - FUEL DELIVERY SYSTEM

Fuel is returned through the fuel pump module
and back into the fuel tank through the fuel filter/
fuel pressure regulator. A separate fuel return line
from the engine to the tank is not used with any gas-
oline powered engine.
The fuel tank assembly consists of: the fuel tank,
fuel pump module assembly, fuel pump module lock-
nut/gasket and rollover valve(s) (refer to 25, Emis-
sion Control System for rollover valve information).
A fuel filler/vent tube assembly using a pressure/
vacuum, 1/4 turn fuel filler cap is used. The fuel
filler tube contains a flap door located below the fuel
fill cap.
Also to be considered part of the fuel system is the
evaporation control system. This is designed to
reduce the emission of fuel vapors into the atmo-
sphere. The description and function of the Evapora-
tive Control System is found in 25, Emission Control
Systems.
Both fuel filters (at bottom of fuel pump module
and within fuel pressure regulator) are designed for
extended service. They do not require normal sched-
uled maintenance. Filters should only be replaced if
a diagnostic procedure indicates to do so.
DIAGNOSIS AND TESTING - FUEL PRESSURE
LEAK DOWN TEST
Use this test in conjunction with the Fuel Pump
Pressure Test and Fuel Pump Capacity Test.
Check Valve Operation: The electric fuel pump
outlet contains a one-way check valve to prevent fuel
flow back into the tank and to maintain fuel supply
line pressure (engine warm) when pump is not oper-
ational. It is also used to keep the fuel supply line
full of gasoline when pump is not operational. After
the vehicle has cooled down, fuel pressure may drop
to 0 psi (cold fluid contracts), but liquid gasoline will
remain in fuel supply line between the check valve
and fuel injectors.
dropped to 0 psi on a cooled down vehicle
(engine off) is a normal condition. When the elec-
tric fuel pump is activated, fuel pressure should
immediately (1–2 seconds) rise to specification.
Abnormally long periods of cranking to restart a
hot engine that has been shut down for a short
period of time may be caused by:
• Fuel pressure bleeding past a fuel injector(s).
• Fuel pressure bleeding past the check valve in
the fuel pump module.
(1) Disconnect the fuel inlet line at fuel rail. Refer
to Fuel Tubes/Lines/Hoses and Clamps for proce-
dures. On some engines, air cleaner housing removal
may be necessary before fuel line disconnection.
(2) Obtain correct Fuel Line Pressure Test Adapter
Tool Hose. Tool number 6539 is used for 5/16" fuel
lines and tool number 6631 is used for 3/8" fuel lines.
(3) Connect correct
Adapter Tool Hose between disconnected fuel line
and fuel rail (Fig. 1).
Fig. 1 Connecting Adapter Tool—Typical
1 - VEHICLE FUEL LINE
2 - TEST PORT "T"
3 - SPECIAL TOOL 6923, 6631, 6541 OR 6539
4 - FUEL PRESSURE TEST GAUGE
5 - FUEL LINE CONNECTION AT RAIL
6 - FUEL RAIL
BR/BE
Fuel pressure that
Fuel Line Pressure
has
Test