Fuel System Diagnosis - Isuzu 1999 RODEO Workshop Manual

6E1–90
RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION
Circuit Description
When the ignition switch is turned ON, the powertrain
control module (PCM) will turn ON the in–tank fuel pump.
The in–tank fuel pump will remain ON as long as the
engine is cranking or running and the PCM is receiving
58X crankshaft position pulses. If there are no 58X
crankshaft position pulses, the PCM will turn the in–tank
fuel pump OFF 2 seconds after the ignition switch is
turned ON or 2 seconds after the engine stops running.
The in–tank fuel pump is an electric pump within an
integral reservoir. The in–tank fuel pump supplies fuel
through an in–line fuel filter to the fuel rail assembly. The
fuel pump is designed to provide fuel at a pressure above
the pressure needed by the fuel injectors. A fuel pressure
regulator, attached to the fuel rail, keeps the fuel available
to the fuel injectors at a regulated pressure. Unused fuel is
returned to the fuel tank by a separate fuel return line.

FUEL SYSTEM DIAGNOSIS

Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart:
2. Connect the fuel pressure gauge to the fuel feed
3. A fuel system that cannot maintain a constant fuel
line as shown in the fuel system illustration. Wrap a
shop towel around the fuel pressure connection in
order to absorb any fuel leakage that may occur
when installing the fuel pressure gauge. With the
ignition switch ON and the fuel pump running, the
fuel pressure indicated by the fuel pressure gauge
should be 283–376 kPa (41–55 psi). This pressure
is controlled by the amount of pressure the spring
inside the fuel pressure regulator can provide.
pressure has a leak in one or more of the following
areas:
f The fuel pump check valve.
f The fuel pump flex line.
D06RX040