Mazda MX-6 1998, Workshop Manual

Page: 69 / 1282

TROUBLESHOOTING [ENGINE CONTROL FS]
STEP INSPECTION ACTION
28 CHECK FUEL INJECTOR LEAKAGE AND
FLOW
• Verify that flow rate for each fuel injector is
within specification using SST (49 L018
901).
• Is flow rate for each injector within
specification?
Yes VERIFY for other leaks.
If none are found, REPLACE fuel pump.
RECHECK fuel pressure.
No
REPLACE damaged fuel injector.
RECONNECT all components.
RECHECK fuel pressure.
29 CHECK VOLTAGE AT FUEL PUMP VEHICLE
HARNESS CONNECTOR
• Key off.
• Disconnect fuel pump harness connector at
fuel pump. Inspect for damaged or pushed
out pins, corrosion and loose wires. Service
as necessary.
• Key on, engine off.
• Connect a digital multimeter between fuel
pump power circuit and fuel pump ground
circuit at fuel pump vehicle harness
connector (refer to Electrical and Vacuum
Troubleshooting Manual for the correct pin
locations).
• Enter Output Test Mode and active fuel
pump circuit. Record voltage reading.
• Is the voltage greater than 10.5 volts?
Yes EXIT Output Test Mode.
RECONNECT fuel pump harness connector.
Go to next step.
No CHECK ground and power circuit.
SERVICE as necessary.
RECHECK fuel pressure.
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 three times.
• Turn key on and engine off, monitor fuel
pressure gauge.
• Does the fuel pressure remain within 34
kPa {0.35 kgf/cm2, 5 psi} of the highest
reading after 10 seconds?
Yes
For Continuous DTCs P1130 and P0171:
Go to step 33.
No For DTCs P0172:
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 the
engine for at least five seconds.
• Was there a pressure drop greater than
34 kPa {0.35 kgf/cm2, 5 psi} while
cranking the engine?
Yes
EEC-V system is not cause of no start.
REMOVE fuel pressure gauge.
tr 0 1 -0 1 A ENGINE SYMPTOM TROUBLESHOOTING
[FS] for future diagnosis.
No REMOVE fuel pressure gauge.
Go to next step.
0 1 -0 1 A -41