Multi-Port Injection Fuel System Diagnosis (Continued)
Chart A-7 (3 of 6)
SUPPLY
RETURN
ONE PIECE FUEL RAIL ASSEMBLY
72573
Check for contaminated fuel tank, struck anti siphon
valve or vacuum leak anywhere before the mechani-
cal fuel pump. Also possible slipping seawater/fuel
pump drive belt.
2. Restricting the fuel return line (Using Special Tool
- Shut-Off Valve) allows the fuel pressure to build
above regulated pressure. With battery voltage
applied to the fuel pump, pressure should rise to
60
PSI (414 kPa) as the fuel return hose is gradu-
TEST DESCRIPTION:
ally pinched.
Number(s) below refer to circled number(s) on the
diagnostic chart.
NOTE: Do not allow fuel pressure to exceed 60 PSI
(414 kPa); damage to the pressure regulator may re-
sult.
1.
Pressure less than 34 PSI (234 kPa) falls into two
areas:
3. This test determines if the high fuel pressure is
due to a restricted fuel return line or a pressure
regulator problem.
•
Regulated pressure less than 34 PSI (234 kPa).
The system will be running lean. Also, hard start-
ing when cold and overall poor performance will
be noticed.
•
Restricted flow causing pressure drop. Normally,
an engine with a fuel pressure of less than 24 PSI
(165
kPa) at idle will not be driveable. However,
if the pressure drop occurs only while underway,
the engine will surge then stop running as pres-
sure begins to drop rapidly. This is most likely
caused by a restricted fuel line or plugged water
separating fuel filter.
Index
5C-62 - ELECTRONIC FUEL INJECTION (MULTI-PORT AND THROTTLE BODY)
90-823224--2 796
| Categories | Mercury MerCruiser Manuals |
|---|---|
| Tags | Mercury MerCruiser 454 CID, Mercury MerCruiser 502 CID |
| Model Year | 1993, 1994, 1995, 1996, 1997 |
| Download File |
|
| Document File Type | |
| Copyright | Attribution Non-commercial |
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