Mazda MX-6 1998, Workshop Manual

Page: 250 / 1282

TROUBLESHOOTING [ENGINE CONTROL KL]
STEP INSPECTION ACTION
30 CHECK SUPPLY FUEL LINE FOR
RESTRICTIONS
• Key off.
• Observe Warnings, Cautions and Notes at
beginning of this Pinpoint Test.
• Disconnect supply fuel line at fuel rail and
at fuel pump.
• Inspect supply line for blockage, kinks or
pinching.
• Apply 21— 34 kPa {0.21— 0.35 kgf/cm2,
3— 5 psi} regulated shop air to supply line
at fuel rail side supply line.
• Does air flow freely through supply line?
Yes Air flows freely.
REPLACE fuel pump.
RECHECK fuel pressure.
No
SERVICE cause of restriction.
RECHECK fuel pressure.
31 CHECK SYSTEM ABILITY TO HOLD FUEL
PRESSURE WITH KEY ON
• Install fuel pressure gauge.
• Cycle key on then off several times.
• Turn key on and engine off, monitor fuel
pressure gauge.
• Does fuel pressure remain within 34 kPa
{0.35 kgf/cm2, 5 psi} of highest reading
after 10 seconds?
Yes For Continuous DTCs P1130, P1150, P0171 and P0174:
Go to step 33.
No For DTCs P0172 and P0175:
Go to step 35.
32 CHECK ABILITY OF FUEL INJECTOR(S) TO
DELIVER FUEL
• Pressure gauge installed.
• Cycle key three times.
• Monitor pressure gauge while cranking
engine for at least five seconds.
• Was there pressure drop greater than 34
kPa {0.35 kgf/cm2, 5 psi} while cranking
engine?
Yes EEC-V system is not cause of no start.
REMOVE fuel pressure gauge.
sr
ENGINE SYMPTOM TROUBLESHOOTING [KL] for
future diagnosis.
No REMOVE fuel pressure gauge.
Go to next step.
33 CHECK RESISTANCE OF FUEL
INJECTOR(S) AND HARNESS
• Key off.
Note
• This erases Continuous Memory DTCs
• Disconnect PCM. Inspect for damaged or
pushed out pins, corrosion and loose wires.
Service as necessary.
• Install breakout box. Leave PCM
disconnected.
Note
• If misfire DTCs are displayed with fuel
control DTCs, use misfire DTCs to
determine fuel injector circuits requiring
testing.
• Measure resistance between suspect fuel
injector Test Pln(s) and Test Pin 71/97 at
breakout box using chart below.
Yes Fuel injector and harness resistance is okay.
Go to step 36.
Cylinder
Number
Test
pin
Cylinder
Number
Test
pin
1
75
4
100
2 101
5 73
3
74
6 99
No Go to next step.
W 6 U 1 0 1 W H K
• Is resistance between 12.0— 16.0 ohms?
0 1 -0 1 B -4 4