Checking Fuel Pump Lift (Vacuum) - Mercury 225 EFI Service Manual

Checking Fuel Pump Lift (Vacuum)

The square fuel pump is designed to lift fuel (vertically) about 60 in. (1524 mm) if there
are no other restrictions in the system using a fuel hose that is 5/16 in. (7.9 mm) minimum
diameter. As restrictions are added, such as filters, fittings, valves etc., the amount of fuel
pump lift decreases.
Fuel pump vacuum and air bubbles in the fuel supply can be checked with a vacuum
gauge, a t-fitting and a clear piece of fuel hose. Connect the clear hose between the inlet
fitting on the pulse driven fuel pump and the vacuum gauge t-fitting, keeping the t-fitting
as close as possible to the pump. Connect the fuel line from the fuel tank to the remaining
connection on the t-fitting.
a - Pulse Driven Fuel Pump
b - Clear hose connected between
pulse pump and "Tee" fitting
90-884294 OCTOBER 2001
a
b
c
d
59157
e
c - Vacuum Gauge (Digital)
d - Tubing Clamp (91-804063)
e - Fuel supply hose from fuel tank
FUEL PUMP
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