Fuel Injector Test; Fuel System Pressure Release Procedure-Without Test Port; Fuel System Pressure Release Procedure-With Test Port - Jeep Wrangler 1997 Manual

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DIAGNOSIS AND TESTING (Continued)
(3) If pressure is at 0 psi, connect DRB scan tool
and refer to the appropriate Powertrain Diagnostics
Procedures service manual .
(4) If operating pressure is above 51 .0 psi, fuel
pump is OK but pressure regulator is defective .
Replace fuel filter/fuel pressure regulator assembly.
FUEL GAUGE SENDING UNIT
The fuel gauge sending unit contains a variable
resistor (track) . As the float moves up or down, elec-
trical resistance will change . Refer to Group 8E,
Instrument Panel and Gauges for Fuel Gauge test-
ing . To test the gauge sending unit only, it must be
removed from vehicle . The unit is part of the fuel
pump module . Refer to Fuel Pump Module Removal/
Installation for procedures . Measure the resistance
across the sending unit terminals . With float in up
position, resistance should be 20 ohms . With float in
down position, resistance should be 220 ohms .
FUEL INJECTOR TEST
To perform a complete test of the fuel injectors and
their circuitry, refer to DRB scan tool and appropri-
ate Powertrain Diagnostics Procedures manual . To
test the injector only, refer to the following :
Disconnect the fuel injector wire harness connector
from the injector. Place an ohmmeter across the
injector electrical terminals . Resistance reading
should be approximately 14 .5 ohms ±1 .2 ohms at
20°C (68°F) .
SEAT-GUIDE
ELECTRICAL
TERMINAL
Fig. 7 Fuel Injector Internal Components-Typical
SERVICE PROCEDURES
PLASTIC
CONNECTOR
FUEL
INLET
FILTER
RETAINER
FUEL SYSTEM PRESSURE RELEASE
PROCEDURE-WITHOUT TEST PORT
Use the following procedure if the fuel rail is
not equipped with a fuel pressure test port.
FUEL SYSTEM 14- 7
(1) Remove fuel pump relay from Power Distribu-
tion Center (PDC). For location of relay, refer to label
on underside of PDC cover.
(2) Start and run engine it stalls .
(3) Attempt restarting engine until it will no
longer run .
(4) Turn ignition key to OFF position.
CAUTION : Steps 1, 2, 3 and 4 must be performed to
relieve high pressure fuel from within the fuel rail .
Do not attempt to use the following steps to relieve
this pressure as excessive fuel will be forced into a
cylinder chamber .
(5) Unplug connector from any injector.
(6) Attach one end of a jumper wire with alligator
clips (18 gauge or smaller) to either injector terminal .
(7) Connect other end of jumper wire to positive
side of battery.
(8) Connect one end of a second jumper wire to
remaining injector terminal .
CAUTION : Supplying power to an injector for more
than 4 seconds will permanently damage the injec-
tor. Do not leave the injector connected to power
for more than 4 seconds .
(9) Momentarily touch
the other end of this
jumper wire to negative terminal of battery for no
more than 4 seconds .
(10) Place a rag or towel below fuel line at quick
connect to rail .
(11) Disconnect quick connect fitting to rail . Refer
to Quick-Connect Fittings in this section .
(12) Return fuel pump relay to PDC .
(13) One or more Diagnostic Trouble Codes (DTC's)
may have been stored in the PCM memory due to
fuel pump relay removal . The DRB scan tool must be
used to erase a DTC . Refer to Group 25, Emission
Control System . See On-Board Diagnostics .
FUEL SYSTEM PRESSURE RELEASE
PROCEDURE-WITH TEST PORT
NOTE : The fuel pressure test port is used on cer-
tain engines only. If equipped, the test port will be
located on the fuel rail (Fig . 4). A sealing cap is
screwed onto the test port.
The fuel system is under constant fuel pressure
(even with the engine off) .
WARNING : BECAUSE THE FUEL SYSTEM IS
UNDER CONSTANT FUEL PRESSURE, THE PRES-
SURE MUST BE RELEASED BEFORE SERVICING
ANY FUEL SYSTEM COMPONENT. THIS DOES NOT
APPLY TO THROTTLE BODY REMOVAL.