Mazda MX-6 1998, Workshop Manual

Page: 248 / 1282

TROUBLESHOOTING [ENGINE CONTROL KL]
STEP INSPECTION
ACTION
21 CHECK PCM CONTROL OF PRC
SOLENOID VALVE
• Key off.
• Breakout box Installed, PCM connected.
• Install digital multimeter between Test Pin
19 and Test Pin 71 of breakout box.
• Record digital multimeter readings under
following conditions:
• Key on, engine off.
• Engine crank.
• Engine running (More than 10 seconds
after start-up).
Note
• PRC solenoid valve should only be
energized during engine crank for previous
conditions.
• Is voltage reading between Pin 19 and
Pin 71 10— 12 V during engine crank and
0— 2 V during other conditions?
Yes PCM is properly controlling PRC solenoid valve.
REMOVE breakout box.
CHECK and REPLACE pressure regulator.
No PCM is not properly controlling PRC solenoid valve.
REMOVE breakout box.
REPLACE PCM.
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
22 CHECK SYSTEM ABILITY TO HOLD FUEL
PRESSURE
• Install fuel pressure gauge Installed.
• Cycle key on and off several times.
• Verify there are no external leaks (Service
as necessary)
• Does fuel pressure remain within 34 kPa
{0.35 kgf/cm2, 5 psi} of highest reading
after one minute?
Yes For Continuous DTCs P1130, P1150, P0171, P0172,
P0174 and P0175:
Go to step 31.
For No Starts:
Go to step 32.
For Fuel Control DTCs displayed with misfire DTCs:
Go to step 33.
All other DTCs:
Go to step 34.
No Excessive pressure loss.
Go to next step.
23 CHECK FUEL PRESSURE LEAKDOWN
• Observe all Warnings, Cautions and Notes.
• Install fuel pressure tester.
• Connect NGS tester.
• Key on, engine off.
• Access Output Test Mode and active fuel
pump to obtain maximum fuel pressure.
• Exit Output Test Mode. Key off.
• Verify fuel pressure remains within 34 kPa
{35 kgf/cm2, 5 psi} of maximum pressure
for 1 minute after turning pump off.
• Does fuel pressure remain within 34 kPa
{0.35 kgf/cm2, 5 psi}?
Yes
Go to step 25.
No Go to next step.
24
CHECK PRESSURE REGULATOR
DIAPHRAGM
• Key off.
• Install fuel pressure tester.
• Start and run engine for 10 seconds.
• Key off. Wait 10 seconds.
• Start and run engine for 10 seconds.
• Key off. Remove vacuum hose from fuel
pressure regulator.
• Inspect for fuel In vacuum hose or regulator
port.
• Is vacuum hose and regulator port free
of fuel?
Yes Go to step 28.
No
REPLACE fuel pressure regulator.
RESET PCM to completely clear DTCs.
tr After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
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