Fuel System
Fuel System Tests
144
Fuel System Tests
Fuel System Pressure Test
Relieve fuel system pressure. Refer to Relieving
Fuel System Pressure on p. 148.
After relieving fuel system pressure, install a 0 to
60 psi (0 to 415 kPa) Fuel Pressure Gauge,
P/N 5007100 or equivalent, to the upper fuel pres-
sure test fitting.
START outboard and check pressure. System
pressure should be 20 to 35 psi (138 to 241 kPa).
Shut OFF outboard. Monitor pressure gauge.
Pressure should not drop below 15 psi (103 kPa).
IMPORTANT: If outboard does not run, prime
fuel system and crank outboard; check circulation
pump operation; check fuel system pressure.
Results:
Normal pressure:
• Observe pressure reading after outboard is shut
OFF
• Refer to Lift Pump Pressure Test on p. 146
Pressure drops after outboard is shut OFF:
• Check for leaking fuel injector.
• Check for leaking pressure regulator.
• Check for external fuel system leak.
High pressure:
• Check for restricted filter or fuel return fitting of
vapor separator, damaged pressure regulator in
vapor separator, or restricted fuel return mani-
fold.
Low pressure:
• Check fuel supply to fuel lift pump. Refer to Lift
Pump Vacuum Test on p. 147. Higher vacuum
readings indicate restrictions in the fuel supply.
Repair or replace as needed.
• Restricted fuel filter/water separator assembly.
• Lift pump not supplying enough fuel to vapor
separator. Refer to Lift Pump Pressure Test
on p. 146.
• If the above tests are good and vapor separator
remains full of fuel, check for damaged circula-
tion pump. Replace vapor separator assembly.
No pressure:
• Check electrical circuit and ground connections
for circulation pump.
• If voltage is present and pump does not run,
repair connection or replace vapor separator
assembly.
Relieve fuel system pressure before removing fuel
pressure gauge. Refer to Relieving Fuel System
Pressure on p. 148.
Pressure Regulator Test
Refer to Vapor Separator Service on p. 150 to
remove vapor separator.
Make sure filter is not clogged. Clean or replace
as needed.
WARNING
Use caution when working on any pressur-
ized fuel system. Wear safety glasses and
work in a well ventilated area. Extinguish all
smoking materials and make certain no open
flames or ignition sources exist. Before start-
ing any fuel system service, carefully relieve
fuel system pressure. Failure to properly
relieve fuel system pressure can result in
spraying fuel and/or excessive fuel spillage
during servicing. Fuel is flammable and can
be explosive under certain conditions.
WARNING
Protect against hazardous fuel spray. Before
starting any fuel system service, carefully
relieve fuel system pressure.
1. Test fitting
2. Fuel pressure gauge
006655
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