Mitsubishi MOTORS Space Runner 1999 Workshop Manual Supplement page 387

13A-28
Code No.56 Abnormal fuel pressure system
Range of check
Ignition switch: ON
Set conditions
Sensor output voltage is 4.8 V or more for four seconds.
or
Sensor output voltage is 0.2 V or less for four seconds.
Range of check
After the engine is started, the following conditions have been detected:
(1) Engine speed: 1,000 r/min or more
(2) Fuel pressure: 2 MPa or more
While engine is running
Set conditions
Fuel pressure is 6.9 MPa or more for four seconds.
or
Fuel pressure is 2 MPa or less for four seconds.
This diagnosis code is also output when air is sucked in high-pressure fuel line
due to no fuel supply.
In this case, air can be bled by letting the engine run at 2,000 r/min for at
least fifteen seconds. After the air bleeding, the diagnosis code must be erased
by the MUT-II.
GDI –
Troubleshooting
Probable cause
Malfunction of the fuel pressure sensor
Open circuit or short-circuited harness wire of the
fuel pressure sensor
Malfunction of the engine-ECU
Malfunction of the fuel pump (high pressure)
Malfunction of the fuel pressure regulator (high
pressure)
Clogged high-pressure fuel line
Air sucking due to no fuel supply