Mitsubishi Electric Lancer Evolution-VII Workshop Manual page 1267

13A-130
Symptom
Fuel pressure too low
D
Fuel pressure drops after racing Fuel pressure drops after racing
D D
No fuel pressure in fuel return
D
hose
Fuel pressure too high
Same fuel pressure when vacuum
hose is connected and when
disconnected disconnected
Symptom
Fuel pressure drops gradually after
engine is stopped engine is stopped
Fuel pressure drops sharply
immediately after engine is stopped
MPI -
On-vehicle Service
14. If any of fuel pressure measured in steps 10 to 13 is out of
specification, troubleshoot and repair according to the
table below.
Probable cause
Clogged fuel filter
Fuel leaking to return side due to poor
fuel regulator valve seating or settled
spring
Low fuel pump delivery pressure
Binding valve in fuel pressure
regulator
Clogged fuel return hose or pipe
Damaged vacuum hose or clogged
nipple
Fuel pressure control system
malfunction
15. 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 injector
Leaky fuel regulator valve seat
Check valve in fuel pump is held open
16. Release residual pressure from the fuel pipe line.
(Refer to P.13A-125.)
17. Remove the fuel pressure gauge and special tool from
the delivery pipe.
Caution
Cover the hose connection with rags to prevent splash
of fuel that could be caused by some residual pressure
in the fuel pipe line.
18. Replace the O-ring at the end of the fuel high pressure
hose with a new one. Furthermore, apply engine oil to
the new O-ring before replacement.
19. Fit the fuel high pressure hose over the delivery pipe
and tighten the bolt to specified torque.
Tightening torque: 5.0 ± 1.0 N·m
20. Check for any fuel leaks by following the procedure in
step 7.
21. Disconnect the MUT-II.
Remedy
Replace fuel filter
Replace fuel pressure regulator
Replace fuel pump
Replace fuel pressure regulator
Clean or replace hose or pipe
Replace vacuum hose or clean nipple
Check the fuel pressure control
system
Remedy
Replace injector
Replace fuel pressure regulator
Replace fuel pump