139
FUEL SYSTEM
FUEL SYSTEM TESTS
7
FUEL SYSTEM TESTS
Fuel System Pressure Test
Relieve fuel system pressure. See Relieving Fuel
System Pressure on p. 143.
After relieving fuel system pressure, install a 0 to
60 p si (0 to 415 kPa ) Fuel Pressur e Gau ge,
P/N 5007100 or equivalent, to the upper fuel pres-
sure test fitting.
START outboard and che ck pressu re. Syste m
pressure should be 20 to 35 psi (138 to 241 kPa).
Shut OFF outbo ard. Mo nitor pr essure gaug e.
Pressure should not drop below 15 psi (103 kPa).
IMPORTANT: If outb oard 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. 141.
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 re stricted filter or fuel return fitting of
vapor separator, damaged pressure regulator in
vapor sep arator, or restricted fuel return mani-
fold.
Low pressure
• Check fuel supply to fuel lift pump. Refer to Lift
Pump Vacuum Test on p. 142. Higher vacuum
readings indicate restrictions in the fuel supply.
Repair or replace as needed.
• Restricted fuel filter/water separator assembly.
• Lift pump not supplying adequate fuel to vapor
separator. Refer to Lift Pu mp Pre ssure Test
on p. 141.
• If the above tests are good and vapor separator
remains full of fu el, check for da maged circula-
tion pump. Replace vapor separator assembly.
No pressure
• Check electrical circuit and ground connections
for circulation pump.
• If volt age 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. 143.
A WARNING
Use cau tion whe n working on any pres-
surized fuel system. W ear sa fety g lasses
and wo rk in a we ll ven tilated area. Extin -
guish all smoking materials and make cer-
tain no open flame s or ign ition sources
exist. Before starting any fuel system ser-
vice, carefully reliev e fuel system pres-
sure. Fai lure to properly relieve fuel
system pressure can result in spraying
fuel and/or e xcessive fuel spill age during
servicing. Fue l is flammab le and can be
explosive under certain conditions.
A WARNING
Protect ag ainst hazardous fue l spray.
Before st arting any fuel syst em service,
carefully relieve fuel system pressure.
1. Fuel pressure gauge
2. Test fitting
004324
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