Service manual

G420F(FE) Service Manual 242 Chapter 7. MPI Gasoune Fuel Delivery System
Inspect Fuel Leakage On Connection
1. Connect the battery negative (-) terminal.
2. Apply battery voltage to the fuel pump terminal
and activate the fuel pump. With fuel pressure
applied, check that there is no fuel leakage from
the fuel pressure gauge or connection part.
Fuel Presure Test
1. Diconnect the negative (-) terminal from the
battery.
2. Connect the fuel pump connector.
3. Connect the battery negative (-) terminal.
4. Start the engine and measure the fuel pressure at
idle.
Standard Value: 350 kpa (3.5 kg/, 49.8 psi)
• If the measured fuel pressure differs from the
standard value, perform the necessary repairs
Condition Probable Cause
Supected
Area
Clogged fuel filter Fuel filter
Fuel
Pressure too
low
Fuel leak on the
fuel-pressure
regulator that is
assembled on fuel
pump because of
poor seating of the
fuel-pressure
regulator.
Fuel Pressure
Regulator
Fuel
Pressure too
High
Sticking fuel
pressure regulator
Fuel Pressure
Regulator
5. Stop the engine and check for a change in the
fuel pressure gauge reading.
After engine stops, the gage reading should hold for
about 5 minutes
• Observing the declination of the fuel pressure
when the gage reading drops and perform the
necessary repairs using the table below.
Condition
Probable
Cause
Supected
Area
Fuel pressure
drops slowly
after engine is
stopped
Injector leak Injector
Fuel pressure
drops
immediately
after engine is
stopped
The check
valve within
the fuel pump
is open
Fuel Pump
Release The Internal Pressure
1. Disconnect the fuel pump connector.
2. Start the engine and wait until fuel in fuel line is
exhausted.
3. After the engine stalls, turn the ignition switch to
OFF position and diconnect the negative (-)
terminal from the battery.
NOTE: Be sure to reduce the fuel pressure before
disconnecting the fuel feed hose, otherwise fuel will
spill out.