Chrysler RAM TRUCK 2500 1994 Service Manual page 945

be found i n the Multi-Port Fuel Injection (MFI)
System—Component Description/System Operation
section of this group.
FUEL PUMP REPLACEMENT
The electric fuel pump is not serviceable. I f the fuel
pump needs replacement, the complete fuel pump
module must be replaced. Refer to Fuel Pump Mod­
ule Removal for procedures. Perform the Fuel System
Pressure Release procedure before servicing the fuel
pump.
F U E L PUMP MODULE REMOWAL
WARNING: T H E F U E L S Y S T E M IS UNDER A CON­
STANT P R E S S U R E (EVEN WITH T H E ENGINE O F F ) .
B E F O R E SERVICING T H E F U E L PUMP MODULE,
F U E L S Y S T E M P R E S S U R E MUST B E R E L E A S E D .
CAUTION: Whenever the fuel pump module Is ser­
viced, the locknut and gasket must be replaced.
(1) Drain the fuel tank. Refer to Draining Fuel
Tank i n the Fuel Tank section of this group.
(2) Remove fuel tank. Refer to the Fuel Tank sec­
tion of this group.
(3) Note the direction of the fuel filter/fuel pres­
sure regulator, the pressure relief/rollover valve and
the fuel pump electrical connector. These should all
be pointed to the drivers side of the vehicle.
(4) The fuel pump module locknut is threaded onto
the fuel tank. Remove the fuel pump module locknut
(Fig. 1). The fuel pump module will spring up when
the locknut is removed.
(5) Remove module from fuel tank.
DISASSEMBLY—FUEL GAUGE SENDING UNIT
(1) Remove sending unit mounting screws (Fig. 1).
(2) Mark the sending unit electrical wires before
removal for correct installation. Carefully disconnect
electrical wires from sending unit. Remove sending
unit.
(3) Reverse order of removal for installation.
IN-TANK FUEL FILTER
The in-tank filter is attached to the bottom of the
fuel pump module (Fig. 2).
(1) Pry the mounting tabs back and remove the in-
tank fuel filter.
(2) Install new fuel filter into retaining tabs.
FUEL PUMP MODULE INSTALLATION
CAUTION: Whenever the fuel pump module is ser­
viced, the locknut and gasket must be replaced.
(1) Using a new gasket, position fuel pump module
into opening i n fuel tank. The fuel filter/fuel pressure
regulator, the pressure relief/rollover valve and the
fuel pump electrical connector should all be pointed
to the drivers side of the vehicle before tightening
locknut.
(2) Position new locknut over top of fuel pump
module.
(3) Tighten locknut.
(4) Install fuel tank. Refer to Fuel Tank Installa­
tion i n this section.
AUXILIARY FUEL SUPPLY FITTING
An auxiliary (capped) fuel supply fitting is located
on the top of the fuel pump module (Fig. 1). This fit­
ting will be available only on diesel powered models,
models with either a 5.9L V-8 heavy duty or 8.0L
V-10 engine and all cab-chassis models. This fitting
supplies a non-pressurized auxiliary fuel source.
FUEL FILTER/FUEL PRESSURE REGULATOR
A combination fuel filter and fuel pressure regula­
tor is used on all gas powered engines. I t is pressed
into a rubber grommet located on the top of the fuel
pump module (Fig. 1). A separate frame mounted fuel
filter is not used with gas powered engines.
F u e l Pressure Regulator Operation: The pres­
sure regulator is a mechanical device that is not con­
trolled by the powertrain control module (PCM) or
engine vacuum.
The regulator is calibrated to maintain fuel system
operating pressure of approximately 241-310 kPa
(35-45 psi) at the fuel injectors. I t contains a dia­
phragm, calibrated springs and a fuel return valve.
The internal fuel filter (Fig. 3) is also part of the as­
sembly.
Fuel is supplied to the filter/regulator by the elec­
tric fuel pump through an opening tube at the bot­
tom of filter/regulator (Fig. 3).
The filter/regulator contains a check valve to main­
tain some fuel pressure when the engine is not oper­
ating. This will help to start the engine.
I f fuel pressure at the pressure regulator exceeds
approximately 45 psi, an internal diaphragm closes
and excess fuel pressure is routed back into the tank
through the pressure regulator. A separate fuel re­
turn line is not used with any gas powered engine.
REMOVAL—FUEL FILTER OR FUEL PRESSURE
REGULATOR
WARNING: T H E F U E L S Y S T E M IS UNDER A CON­
STANT P R E S S U R E , E V E N WITH ENGINE OFF. B E ­
F O R E SERVICING T H E F U E L F I L T E R / F U E L
P R E S S U R E R E G U L A T O R , T H E F U E L S Y S T E M
P R E S S U R E MUST B E R E L E A S E D .
Refer to Fuel System Pressure Release i n the Fuel
Delivery System section of this group.
The fuel filter/fuel pressure regulator is located on
the top of fuel pump module (Fig. 4).