GDI ± On-vehicle Service
13A-96
5. Connect the MUT-II to the diagnosis connector.
6. Turn the ignition switch to ON. (But do not start the engine.)
7. Select ªItem No.07º 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 328 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.
Symptom Probable cause Remedy
D Fuel pressure too low
p
p
Clogged fuel filter Replace fuel filter
D
ue
pressure
rops a
er rac
ng
Fuel leaking to return side due to poor
fuel pressure regulator (low pressure)
valve seating or settled spring
Replace fuel pressure regulator
(low pressure)
Low fuel pump (low pressure) delivery
pressure
Replace the fuel pump (low pressure)
Fuel pressure too high
Binding valve in fuel pressure regula-
tor (low pressure)
Replace fuel pressure regulator
(low pressure)
Clogged fuel return hose or pipe Clean or replace 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.
Symptom Probable cause Remedy
Fuel pressure drops gradually after
engine is stopped
Leaky fuel pressure regulator (low
pressure) valve seat
Replace fuel pressure regulator
(low pressure)
Fuel pressure drops sharply
immediately after engine is stopped
Check valve in fuel pump (low
pressure) is held open
Replace the fuel pump (low pressure)
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