Perkins M300TI Installation Manual page 39

TPD1317e Chapter 6
In some applications there may be legislation that requires that fuel lines draw from, and return to , the top of
the tank. Figure 2 shows an acceptable arrangement.
The fuel returned to the tank
should be kept away from
the main fuel feed, to avoid
recirculation.
Fuel tank
Main fuel feed
Water separator
Figure 2 - A simple fuel system with connections through the top of the tank
The fuel tank may be steel, aluminium, or G.R.P. or, alternatively, a rubber bag tank may be used. The main
fuel connection is taken from the rear of the tank so that all the fuel is available for use when under way when
the hull will be at an angle. The fuel return is extended within the tank to near the bottom in order to prevent
air locks which can arise due to syphoning of the fuel when the engines are stopped.
From the tank the main engine feed line goes first to a water separator, preferably one fitted with a thick clear
plastic bottom and a drain cock. The fuel lines may be of metal, either copper or 'bundy' steel tubing used
either with compression fittings or preferably soldered nipples, with a flexible armoured rubber hose to connect
to the fuel lift pump.
This simple fuel system is satisfactory when one or more engines are run from a single fuel tank, and it may
also be used when there are two tanks each supplying one engine. In the latter case the system may include
a cross connection, between the tanks by means of a balancing pipe, with a valve, at each end. In some
installations cross connecting pipes between the two engine feed pipes and the two engine return pipes have
been used, but valves are necessary in every line so that the appropriate system may be selected, and the
complexity of installation and operation is such that the advantages in operating flexibility are out-weighed by
the possibility of obscure problems due to component malfunctions, incorrect operation or engine interaction.
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