Mercury 305 CID - Page 604

NOT OK
1
3
4
• START AND IDLE ENGINE AT
NORMAL OPERATING
TEMPERATURE.
• PRESSURE SHOULD BE LOWER
BY 3-10 PSI (21-69 kPa).
• INSTALL FUEL PRESSURE GAUGE, 91-16850 .
• IGNITION “OFF” FOR 10 SECONDS.
• IGNITION “ON.” FUEL PUMP WILL RUN FOR ABOUT 2 SECONDS.
• NOTE FUEL PRESSURE, WITH PUMP RUNNING, SHOULD HOLD
STEADY WHEN PUMP STOPS.
FROM
CHART A-3
(2 OF 4)
OK
NOT OK
NO TROUBLE FOUND.
REVIEW THE TROUBLE-
SHOOTING SECTION.
OK
PRESSURE BELOW
34 PSI (234 kPa)
PRESSURE ABOVE
38 PSI (262 kPa)
NO
PRESSURE
PRESSURE BUT
NOT HOLDING
• USING AN EXTERNAL
VACUUM SOURCE, APPLY 10
INCHES OF VACUUM TO FUEL
PRESSURE REGULATOR.
• FUEL PRESSURE SHOULD DROP
3-10 PSI (21-69 kPa).
• IGNITION “OFF” FOR
10 SECONDS.
• IGNITION “ON.”
• BLOCK FUEL PRESSURE LINE USING
SPECIAL TOOL (SHUT-OFF VALVE)
• PRESSURE SHOULD HOLD.
SEE
CHART A-7
4 OF 6
• IGNITION “OFF.”
• APPLY 12 VOLTS TO FUEL
PUMP CONNECTOR(GRAY
WIRE).
• LISTEN FOR FUEL PUMP
RUNNING.
NOT HOLDING HOLDS
NOT OK
REPAIR VACUUM
SOURCE TO
REGULATOR.
OK
REPLACE
REGULATOR
ASSEMBLY.
• IGNITION “OFF” FOR 10 SECONDS.
• IGNITION “ON.”
• BLOCK FUEL RETURN LINE USING
SPECIAL TOOL (SHUT-OFF VALVE)
• RECHECK PRESSURE.
CHECK:
• LEAKING PUMP FITTINGS,
OR HOSE.
• FAULTY VST PUMP.
NOT HOLDINGHOLDS
FAULTY FUEL PRESSURE
REGULATOR.
LOCATE AND CORRECT
LEAKING INJECTOR(S).
PUMP NOT RUNNINGPUMP RUNS
CHECK FOR:
• RESTRICTED FUEL LINE.
• DISCONNECTED HOSE
IF OK
CHECK FOR:
• OPEN WIRE IN CKT 120.
• OPEN PUMP GROUND
CKT 150.
IF OK
REPLACE ELECTRIC FUEL PUMP.
2
NOTE: THE IGNITION MAY HAVE TO BE CYCLED
“ON” MORE THAN ONCE TO OBTAIN MAXIMUM
PRESSURE. ALSO, IT IS NORMAL FOR THE PRESSURE
TO DROP SLIGHTLY WHEN THE PUMP STOPS.
ELECTRONIC FUEL INJECTION (MULTI-PORT AND THROTTLE BODY) - 5E-6390-823225--1 1096
Multi-Port Injection Fuel System Diagnosis (Continued)
Chart A-7: (2 of 6)