Mitsubishi FUEL Manual page 317

Symptom
D Fuel pressure too low
Fuel pressure drops after racing
D
Fuel pressure too high
Symptom
Fuel pressure drops gradually after
engine is stopped
Fuel pressure drops sharply immedi-
ately after engine is stopped
GDI -
On-vehicle Service
5. Connect the MUT-II to the diagnosis connector.
Caution
Turn off the ignition switch before disconnecting or
connecting the MUT-II.
6. Turn the ignition switch to ON. (But do not start the engine.)
7. Select "Item No. 07" from the MUT-II Actuator test to
drive the fuel pump (low pressure) at the fuel tank side.
Check that there are no fuel leaks from any parts.
8. Finish the actuator test or turn the ignition switch to OFF.
9. Start the engine and run at idle.
10. Measure fuel pressure while the engine is running at
idle.
Standard value: approximately 324 kPa
11. Check to see that fuel pressure at idle does not drop
even after the engine has been raced several times.
12. If fuel pressure is out of the standard value, troubleshoot
and repair according to the table below.
Probable cause
Clogged fuel filter
Fuel leaking to return side due to poor
fuel pressure regulator (low pressure)
valve seating or settled spring
Low fuel pump (low pressure)
delivery pressure
Binding valve in fuel
regulator (low pressure)
Clogged fuel return hose or pipe
13. Stop the engine and check change of fuel pressure gauge
reading. Normal if the reading does not drop within 2
minutes. If it does, observe the rate of drop and
troubleshoot and repair according to the table below.
Probable cause
Leaky fuel pressure regulator (low
pressure) valve seat
Check valve in fuel pump (low
pressure) is held open
14. Release residual pressure from the fuel pipe line. (Refer
to P.13I-121.)
Remedy
Replace fuel filter
Replace fuel pressure regulator
(low pressure)
Replace the fuel pump (low pressure)
pressure Replace fuel pressure regulator
(low pressure)
Clean or replace hose or pipe
Remedy
Replace fuel pressure regulator
(low pressure)
Replace the fuel pump (low pressure)
13I-123