182
FUEL SYSTEM
FUEL SYSTEM TESTS
START outboard and run at FULL THROTTLE for
at least two minutes. Monitor clear vinyl hose for
the presence of air. Air bubbles indicate a faulty
hose, connection, or fuel tank pick-up. Repair, if
necessary, before proceeding.
There should be no air or vapor bubbles visible in
the clear hose. The maximum inlet fuel vacuum
should not exceed 4 in. Hg. (13.5 kPa) at the inlet
to the fuel lift pump under any operating condi-
tions (IDLE to WOT).
A higher vacuum indicates an excessive restric-
tion in the fuel supply. Repair as needed. Refer to
Fuel System Requirements on p. 35 for fuel sup-
ply component requirements.
Lift Pump Diaphragm Test
Perform this test only if a damaged pump is sus-
pected. This test does not check the performance
of internal fuel pump check valves.
Remove both pulse hoses from the crankcase fit-
tings.
Apply 15 psi (103 kPa) to each of the pulse hoses
of the pump. Replace lift pump if either side of
pump fails to hold pressure.
Anti-Siphon Valve Test
Remove anti-siphon valve from fuel tank. Install
adapter fittings and a 36 in. (91.4 cm) length of
clear hose to the inlet side (tank end) of valve.
Fill clear hose with water to a height of 20 in. (500
mm). Water must NOT flow through valve. An
occasional drip is acceptable. Replace valve if
water drips continuously.
Increase height of water to 25 in. (630 mm). Water
should flow through valve as water level reaches
25 in. (630 mm). Replace the anti-siphon valve if
test results are different.
1. Pulse fitting 000670
1
1. Anti-siphon valve
2. Adapter fitting
3. Clear hose
DR2277
1
3
2
20 in. (500 mm)
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