Mercury 100 FourStroke, Service Manual

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90-830234R3 DECEMBER 1997 FUEL SYSTEM - 3A-11
Troubleshooting Fuel Pump
(continued)
PROBLEM: Lack of Fuel Pump Pressure
Possible Cause Corrective Action
Hole in pulse hose
(1 pulse hose). Replace pulse hose.
Loose pulse hose. Tighten connection.
Boost diaphragm gasket
distorted or out of place. Check seal between mating
surfaces where “rib” divides
pulse chamber – gasket
must align with rib; check for
distorted gasket. Align or
replace gasket if necessary.
Removal
•
Disassemble by removing 2 hex-head bolts; re-
move/disassemble fuel pump parts.
53992
a
a
a - Bolts – Fuel Pump
Fuel Pump –
Cleaning/Inspection
Clean fuel pump housing, check valves, pulse cham-
ber, and pump base in solvent, and dry all but check
valves with compressed air.
Inspect each check valve (2 ea.), for cracks and/or
holes. Check each black rubber disc (2 ea.) to see
that the black coating is not coming off. Unless dam-
aged while disassembled, replacement is seldom
necessary. Inspect the Check Valve Assembly on
Chamber Plate (check by both pressure and suction
to hose barb), to see that check ball is moving and
functioning (1-3 psi (6.8 – 20.5 kPa required).
Inspect fittings on fuel pump housing for looseness
or any signs of fuel or air leaks. Replace or tighten fit-
ting if leak is found, or replace chamber Plate Assem-
bly.
Check Valve Reassembly
1. Insert retainer thru plastic disc and rubber check
valve.
51530
a
b
c
a - Retainer
b - Plastic Disc
c - Check Valve