Mitsubishi MOTORS Space Runner 1999 Workshop Manual Supplement page 459

13A-100
Symptom
Fuel pressure too low
Fuel pressure drops after racing Fuel pressure drops after racing
Fuel pressure too high
Symptom
Fuel pressure drops gradually after
engine is stopped
Fuel pressure drops sharply
immediately after engine is stopped
GDI –
On-vehicle Service
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 pressure regula-
tor (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.13A-102.)
15. Remove the fuel pressure gauge and special tools from the
fuel pump (high pressure).
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.
16. Replace the O-ring at the end of the high-pressure fuel
hose with a new one. Furthermore, apply engine oil to
the new O-ring before replacement.
17. Fit the high-pressure fuel hose to the fuel pump (high
pressure) and tighten the mounting bolt to specified torque.
18. Check for any fuel leaks by following the procedure in
step 7.
19. Disconnect the MUT-II.
Remedy
Replace fuel filter
Replace fuel pressure regulator
(low pressure)
Replace the fuel pump (low 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)