181
FUEL SYSTEM
FUEL SYSTEM TESTS
8
Circulation Pump Resistance Test
Disconnect the battery cables at the battery.
Use a digital multimeter to measure the fuel pump
circuit and coil resistance.
Lift Pump Pressure Test
Install a 0 to 15 psi (0 to 103 kPa) Fuel Pressure
Gauge, P/N 5006397 or equivalent, to the lower
fuel pressure test fitting.
Prime the fuel system and check for leaks. START
outboard and run at idle speed. Hold gauge level
with inlet fitting and monitor gauge for pressure
reading.
Pressure should stabilize and gauge must not
indicate less than 3 psi (21 kPa).
Results:
Normal pressure
• Perform the Lift Pump Vacuum Test on
p. 181. Make sure no air leaks or restrictions
exist in the fuel supply hose or boat fuel system.
Low pressure:
• Check pulse hoses and fittings for restrictions.
• Perform the Lift Pump Vacuum Test on
p. 181. Make sure no air leaks or restrictions
exist in the fuel supply hose or boat fuel system.
• Check fuel flow through fuel lift pump. Use fuel
primer bulb to force fuel through pump.
No pressure:
• Check pulse hoses and fittings restrictions.
• Check fuel flow through fuel lift pump. Use fuel
primer or primer bulb to force fuel through
pump.
• Momentarily prime or squeeze primer bulb to
check gauge operation.
• Check pulse hose and fittings for restrictions.
Lift Pump Vacuum Test
Confirm fuel supply to the fuel lift pump.
Temporarily install a vacuum gauge, T-fitting, and
8 in. (20.3 cm) of clear vinyl hose between the fuel
supply hose and fuel lift pump (inlet). Secure con-
nections with tie straps to prevent fuel or air leaks.
IMPORTANT: Do not use fuel primer bulb, man-
ual fuel primer, or electric fuel pump primer to
restart outboard. A positive pressure in the fuel
supply could damage some vacuum gauges.
Fuel Pump Resistance
3 Ω @ 77°F (25°C)
005438
1. Fuel pressure gauge
2. Test fitting
005439
1
2
000243
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