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below the height of the fuel system. It is recommended that an
anti-siphon valve be included in the fuel tank.
A 3/8” minimum (inner-dimension) “Type A1” USCG Approved
tubing is recommended for the fuel line from the tank to the
engine for all 181/3.0L, 262/4.3L and 350/5.7L engines. All
7.4L and larger engines must be 1/2” minimum inner dimen-
sion. It should be adequately secured and provided with a
flexible section near the engine to reduce vibration to the line.
Fittings for the tubing should conform to current Coast Guard or
American Boating & Yacht Council standards. It is also
recommended that older copper fuel lines be replaced with an
approved fuel line.
Fuel tanks should be of a size adequate with the full require-
ments and should be anchored securely and vented in such a
manner to conform to Coast Guard regulations. The fuel tank
filling arrangements should conform to all safety regulations,
and must be outboard. The installation of an approved fuel
shut off valve at the tank is mandatory.
Verify that carbureted engines have 5 - 7 psi fuel pressure.
EFI engine fuel pressure should meet original manufacturers
specifications.
WARNING: INADEQUATE FUEL PRESSURE
WILL DESTROY A NEW ENGINE.
Crankcase Ventilation
Open vent tubes maybe routed directly to flame arrestor. If
PVC valves are used, they must be routed to a vacuum port on
the carburetor base or intake manifold.
Exhaust Piping
IMPORTANT!
The boat manufacturer or installing dealer (or
individual) is responsible for properly locating the engine and
installing the exhaust system. Improper installation may allow
water to enter the exhaust manifolds and engine cylinders and
severely damage the engine. Damage caused by water in the
engine will not be covered by the MARINE POWER Warranty,
unless this damage is a result of defective parts or workman-
ship by MARINE POWER.
ENPACS, SPORTPACS, and TOWPACS are equipped with a
wet exhaust system in which exhaust is mixed with water in
the exhaust risers. This water cools the exhaust and allows
the use of heat resistant rubber hose on the riser outlets.
Follow these general guidelines when designing and install-
ing the exhaust system.
Use heat resistant hose that complies with specifications SAE
J2006 or UL 1129 (ABYC standard). Exhaust hoses should be
4” on dual outlet systems. 8.2L and larger engines should use
5” on single outlet systems.
Sharp bends should be avoided.
Exhaust hoses should be connected straight on the riser
outlets.
Exhaust back pressure test should be preformed to ensure
that exhaust components are adequately sized. Exhaust back
pressure should be between 1-3 psi. Some back pressure is
necessary to prevent water intrusion. Do not go below 1 psi.
Exhaust risers must be the suggested distance above the
water line. Install riser spacers if necessary.
A minimum of 18” of exhaust hose must be installed
between the exhaust risers and the collector, Y-pipe,
muffler or first angular fitting. This portion of the
exhaust hose must have a downward slope of
1-1/4”/ft.
for conventional inboards and a downward slope
of 7/8”/ft. for V-drives.
Some OEM installations may
different from these specifications but these installations
have been carefully evaluated by MARINE POWER and the
OEM.
After the first 18” the exhaust system must have a drop of
1/2”/ft. Measure exhaust riser height as shown. Minimum
exhaust riser height should be 15” on 7.4 and 8.2L engines.
All others should be 13”.
The slope in the exhaust hose and components must be routed
so that no low point exists in the system where water may
be retained. The muffler, collector and exhaust hoses must be
adequately supported for proper routing and to prevent over-
stressing the exhaust manifolds and risers.
Internal flappers may be required on naturally aspirated 7.4
and 8.2L engines.
Applications with through transom exhausts must be equipped
with exhaust flappers to prevent the reverse flow of water into
the engine. Exhaust outlets should be above the water line
with the boat at rest to minimize engine back pressure.
Every exhaust connection should be secured with at
least two hose clamps. The clamps should be stainless
steel and at least 1/2” wide.
3.
Precautions/Instructions
