Diagnosis And Testing - Fuel Pump Pressure Test; Diagnosis And Testing - Fuel Pump Amperage Test - Dodge 2001 Ram 1500 Owner's Manual

14 - 10 FUEL DELIVERY - GASOLINE
FUEL PUMP (Continued)
DIAGNOSIS AND TESTING - FUEL PUMP
PRESSURE TEST
Use this test in conjunction with the Fuel Pump
Capacity Test, Fuel Pressure Leak Down Test and Fuel
Pump Amperage Test found elsewhere in this group.
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.
All fuel systems are equipped with a fuel tank
module mounted, combination fuel filter/fuel pressure
regulator. The fuel pressure regulator is not con-
trolled by engine vacuum.
WARNING: THE FUEL SYSTEM IS UNDER CON-
STANT FUEL PRESSURE EVEN WITH THE ENGINE
OFF. BEFORE DISCONNECTING FUEL LINE AT
FUEL RAIL, THIS PRESSURE MUST BE RELEASED.
REFER TO THE
RELEASE PROCEDURE.
(1) Remove protective cap at fuel rail test port.
Connect the 0–414 kPa (0-60 psi) fuel pressure gauge
(from gauge set 5069) to test port pressure fitting on
fuel rail (Fig. 11). The DRB III Scan Tool along
with the PEP module, the 500 psi pressure
transducer, and the transducer-to-test port
adapter may also be used in place of the fuel
pressure gauge.
(2) Start and warm engine and note pressure
gauge reading. Fuel pressure should be 339 kPa
kPa (49.2 psi 5 psi) at idle.
(3) If engine runs, but pressure is below 44.2 psi,
check for a kinked fuel supply line somewhere
between fuel rail and fuel pump module. If line is not
kinked, but specifications for either the Fuel Pump
Capacity, Fuel Pump Amperage or Fuel Pressure
Leak Down Tests were not met, replace fuel pump
module assembly. Refer to Fuel Pump Module
Removal/Installation.
(4) If operating pressure is above 54.2 psi, electric
fuel pump is OK, but fuel pressure regulator is defec-
tive. Replace fuel filter/fuel pressure regulator. Refer
to Fuel Filter/Fuel Pressure Regulator Removal/In-
stallation for more information.
(5) Install protective cap to fuel rail test port.
Fuel pressure that
FUEL SYSTEM PRESSURE
has
Fig. 11 Fuel Pressure Test Gauge (Typical Gauge
1 - SERVICE (TEST) PORT
2 - FUEL PRESSURE TEST GAUGE
3 - FUEL RAIL
DIAGNOSIS AND TESTING - FUEL PUMP
AMPERAGE TEST
This amperage (current draw) test is to be done in
conjunction with the Fuel Pump Pressure Test, Fuel
Pump Capacity Test and Fuel Pressure Leak Down
Test. Before performing the amperage test, be sure the
temperature of the fuel tank is above 50° F (10° C).
The DRB Scan Tool along with the DRB Low Cur-
rent Shunt (LCS) adapter (Fig. 12) and its test leads
will be used to check fuel pump amperage specifications.
34
Fig. 12 Low Current Shunt
1 - LOW CURRENT SHUNT ADAPTER
2 - PLUG TO DRB
3 - TEST LEAD RECEPTACLES
Installation at Test Port)
BR/BE