Fuel System - Mercury D4.2L Manual

CE406

Fuel System

Absolute cleanliness is required for work on the fuel system, fuel injection components have very
close tolerances. Even minute particles of dirt or small amounts of water can impair the function of the
fuel injection system.
FUEL TANK CLEANING AND FLUSHING
IMPORTANT: Diesel fuel should not be left in tank during winter storage, as an accumulation of rust,
sludge and wax residue will form.
1
Refer to boat manufacturer's instructions and clean fuel tank at specified intervals. Unless specified other-
wise, flush and clean diesel fuel tank every 1000 hours or 5 years, whichever occurs first.
CD654
HAND PUMP/PRIMER
2
A plunger-type of hand pump/primer is located on the fuel filter bracket and is used to: (1) refill fuel system
if system was run dry; (2) refill fuel filter when changing filter; or (3) to prime the fuel system if engine has not
been run for a while. To operate the hand pump/primer, move the plunger (upper portion) up and down as
needed.
A
D3.6L and D4.2L Models.
B
D2.8L D-Tronic, D4.2L D-Tronic and D4.2L LD Models.
CD655
PRIMING FUEL SYSTEM
3
Prime engine if it has not been run for a while or if engine will not start. Move the hand pump/primer plunger
up and down several times as previously outlined. Attempt to start engine.
A
D3.6L and D4.2L Models.
B
D2.8L D-Tronic, D4.2L D-Tronic and D4.2L LD Models.
CD656
FILLING FUEL FILTER
NOTE: Follow this procedure after installing new filter or if fuel has been drained from filter checking for water.
4
Loosen bleed screw on fuel filter bracket. As previously outlined, move plunger on hand pump/primer up and
down repeatedly, until an air free stream of fuel flows from bleed screw. Filter is full when this occurs. Tighten
bleed screw.
A
D3.6L and D4.2L Models.
B
D2.8L D-Tronic, D4.2L D-Tronic and D4.2L LD Models.
CD657
FILLING (BLEEDING) FUEL SYSTEM
NOTE: Follow this procedure if fuel system was run dry or if part of fuel system was drained for a service function.
Fill fuel system up to the point that fuel filter is full following previous procedure (Filling Fuel Filter); then, ensure
that bleed screw on fuel filter bracket is closed.
5
On D3.6L, D4.2L and D4.2L LD Only: Loosen, DO NOT REMOVE, bleed screw on fuel injection pump (lo-
cated between fuel line connection fittings on injection pump). Continue to repeatedly move plunger on hand
pump/primer, until an air-free stream of fuel flows from injection pump bleed screw. Tighten bleed screw.
CAUTION
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