Installation manual

90-898305
4-10
VACUUM TEST
The system vacuum test is normally performed at an idle speed. As engine
RPM increases, there will be a slight increase in vacuum; this increase should
not exceed normal readings at any RPM.
Normal Reading Below 2.5 in. of Vacuum (mercury)
Reading above 2.5 in. of vacuum
(mercury)
Restriction within the fuel system
• Restricted anti-siphon valve
• Restricted or malfunctioning
primer bulb
• Kinked or collapsed fuel hose
• Plugged water separating fuel
filter (in the boat)
• Restriction in fuel line thru-hull
fitting
• Restriction in fuel tank switching
valves
• Plugged fuel tank pick-up screen
Correction:
If the fuel capability test indicated good vacuum level (2.5 in. mercury or
higher) proceed to PRIMER BULB replacement.
If the fuel pump capability test indicate low vacuum, proceed with the following
two upgrades to the fuel system to prevent low speed stalling.
PULSE FUEL PUMP:
The new repair kits contain check valves made of a plastic material,
impervious to damage from fuel additives. When repairing the fuel pump
discard old rubber and small plastic check valve disks, and install one new
plastic disk under each retainer. Caution must be taken not to push the check
valve retainer too tightly against the check valve, this may cause the valve to
deform.
Notes
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