Dodge 2000 DURANGO Service Manual page 728

14 - 8 FUEL SYSTEM
DIAGNOSIS AND TESTING (Continued)
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 in this section
of the group for procedures. 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. 8).
(4) Connect the 0-414 kPa (0-60 psi) fuel pressure
test gauge (from Gauge Set 5069) to the test port on
the appropriate Adaptor Tool. 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.
The fittings on both tools must be in good
condition and free from any small leaks before
performing the proceeding test.
(5) Start engine and bring to normal operating
temperature.
(6) Observe test gauge. Normal operating pressure
should be 339 kPa
(7) Shut engine off.
(8) Pressure should not fall below 30 psi for five
minutes.
(9) If pressure falls below 30 psi, it must be deter-
mined if a fuel injector, the check valve within the
fuel pump module, or a fuel tube/line is leaking.
(10) Again, start engine and bring to normal oper-
ating temperature.
(11) Shut engine off.
(12) Testing for fuel injector or fuel rail leak-
age: Clamp off the rubber hose portion of Adaptor
Tool between the fuel rail and the test port "T" on
Fuel pressure that
Fuel Line Pressure
34 kPa (49.2 psi 5 psi).
has
Fig. 8 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
Test
5 – FUEL LINE CONNECTION AT RAIL
6 – FUEL RAIL
Adapter Tool. If pressure now holds at or above 30
psi, a fuel injector or the fuel rail is leaking.
(13) Testing for fuel pump check valve, filter/
regulator check valve or fuel tube/line leakage:
Clamp off the rubber hose portion of Adaptor Tool
between the vehicle fuel line and test port "T" on
Adapter Tool. If pressure now holds at or above 30
psi, a leak may be found at a fuel tube/line. If no
leaks are found at fuel tubes or lines, one of the
check valves in either the electric fuel pump or filter/
regulator may be leaking.
Note: A quick loss of pressure usually indicates a
defective check valve in the filter/regulator. A slow
loss of pressure usually indicates a defective check
valve in the electric fuel pump.
The electric fuel pump is not serviced separately.
Replace the fuel pump module assembly. The filter/
regulator may be replaced separately on certain
applications. Refer to Fuel Filter/Fuel Pressure Reg-
ulator Removal/Installation for additional informa-
tion.
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
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