Mercury MerCruiser MCM 454 Mag MPI Service Manual page 442

SERVICE MANUAL NUMBER 23
Only a few points related to function and safety are listed here. Refer to boating standards
(NMMA, ABYC, etc.) and Coast Guard regulations for complete guidelines.
It is recommended that the exact route and length of the fuel lines be established at the first
installation of the engine to prevent problems later in connecting them to the engine.
All fuel lines must be well secured. The holes where the lines run through the bulkheads
should be carefully rounded off or protected with rubber grommets. This prevents damage
to the lines from abrasion.
The following, but not limited to the following, additional fuel connection related points,
applying to all engines unless otherwise stated , must be considered. Refer to boating
standards (NMMA, ABYC, etc.) and Coast Guard regulations for complete guidelines.
NOTE: If an Anti-Syphon valve is required for a particular application, it is recommended
that an Electric Anti-Syphon Valve be used. This type of anti-syphon valve may help prevent
vapor-locking when reformulated fuels or fuels with high reed-vapor pressure are used.
1. Fuel pickup should be at least 1 in. (25mm) from the bottom of fuel tank to prevent
2. Fuel lines used must be Coast Guard approved (USCG Type A1).
Diameter of fittings and lines must not be smaller than 3/8 in. (10 mm) I.D. on 454 CID/7.4L
and 502 CID/8.2L engines.
3. On Multi-Engine Gasoline Installations: It is best to use a fuel pickup and supply line
4. Larger diameter (than previously specified) lines and fittings must be used on
5. Fuel line(s) should be installed free of stress and firmly secured to prevent vibration
6. Sharp bends in fuel lines should be avoided.
7. A flexible fuel line must be used to connect fuel supply line to fuel inlet fitting on engine
Index
90-861326--1 MARCH 1999
Downloaded from https://needmanual.com/
All connections should be on the upper side of the tank.
The drain plug at the lowest point on the tank serves to permit the removal of water and
sediment.
The filler pipe outer diameter should be at least 2 in. (50mm).
The tank breather pipe must have an inner diameter of at least 1/2 in. (13mm) and must
be fitted with a swan neck to prevent water from entering the tank.
picking up impurities.
for each engine. If a single pickup and line is used, line must not be smaller than 1/2 in.
(13mm) I.D.
installations requiring long lines or numerous fittings.
and/or chafing.
to absorb deflection when engine is running.
FUEL DELIVERY SYSTEM FOR ELECTRONIC FUEL INJECTION
Page 5A-5