Mariner Mercury 105/140 JET, Service Manual

Page: 301 / 797

3D-28 - FUEL SYSTEMS 90-824052R3 JUNE 2002
Vapor Separator Float Test
Purpose: This test will indicate if float is stuck in the
up position.
NOTE: If float is stuck down, vapor separator will
over flow causing a rich condition.
1. Remove fuel inlet hose from vapor separator and
put end of hose in clean container.
2. Remove all spark plugs from engine to prevent
engine from starting.
3. Turn ignition key switch to “START” position and
operate starter motor for 15 to 20 seconds.
OFF
ON
START
4. Look for fuel flow from hose.
55178
Results: If fuel flow is present at hose, remove,
disassemble and inspect float assembly. See
vapor separator disassembly.
If fuel flow is low or not present, perform Water
Separating Filter Flow Test.
Water Separating Filter Flow Test
Purpose: This test will indicate if water separating
filter is clogged.
1. Remove fuel inlet hose to water separating filter.
Put end of hose in clean container.
2. Place emergency stop switch in OFF position to
prevent engine from starting. If boat is not
equipped with a emergency stop switch, connect
a jumper lead from the BLACK/YELLOW
terminal on the switch box to engine ground.
3. Turn ignition key switch to “START” and operate
starter motor for 10 to 20 seconds.
OFF
ON
START
4. Look for fuel flow from hose.
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Results: Fuel flows from water separating inlet hose.
Remove and replace clogged filter.
Low or no fuel flow from water separating inlet hose.
Perform pulse fuel pump delivery test.