179
FUEL SYSTEM
FUEL SYSTEM TESTS
8
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. 181.
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. 181. 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. 181.
• 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 fue
pressure gauge. Refer to Relieving Fuel System
Pressure on p. 183.
Pressure Regulator Test
Refer to Vapor Separator Service on p. 185 to
remove vapor separator.
Make sure filter is not clogged. Clean or replace
as needed.
Apply oil to valve and connect pressure pump and
hose to the fuel return fitting of vapor separator.
Apply pressure to check regulator operation. The
pressure should open check valve at approxi-
mately 15 psi (103 kPa).
Vapor Separator Vent Check
Monitor the vapor separator vent hose. No fuel or
a trace of fuel is acceptable. Excessive fuel dis-
charge indicates a vapor separator vent malfunc-
tion. Monitor vent for presence of fuel during
testing. Temporarily install clear tubing for moni-
toring. Replace vapor separator if the venting of
fuel is continuous.
1. Filter
2. Fuel return fitting
3. Pressure regulator
000249r
2
13
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