F17099-1 Force HOUSING

Ensure that flexible fuel hose routing avoids coming into contact with parts of the engine which can lead to abrasion of the hose.
Fuel Tanks
Fuel tanks should have the following features:* The filler neck should be raised so that water will not enter when filling.* The filler cap should seal effectively to prevent water entering when under way.* A vent pipe should be fitted, again in such a way as to avoid the entry of water.* The tank should have a sump or angled bottom with a drain tap so that water and sediment can be removed. (This is not always possible).* Internal baffles may be required to prevent fuel surge.* The tank should have a removable panel to simplify cleaning.* The fuel pipework should be as simple as possible with the minimum of valves and cross connections, so that obscure fuel feed problems are minimized.* A fuel sedimenter (water separator) is required in the fuel system between the fuel tank and the engine mounted lift pump. To avoid problems when venting air after draining the sedimenter, it should preferably be installed below the normal minimum level of fuel in the fuel tank. (This is not always possible!).* The tank should have at least two connections; a fuel feed connection, and a fuel return connection. Whenever possible a tank should only supply one engine, but in any case each engine should have its own fuel pipes, from tank to engine.Typical Fuel Systems
The more simple the fuel system, the better it will perform in service. Figure (A) shows an ideal system. In some applications there may be legislation that requires that fuel lines draw from and return to, the top of the tank. Figure (B) shows an acceptable arrangement. The fuel tank may be steel, aluminium, or G.R. P. (Glass Reinforced Plastic) 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 seamless steel tubing used either with compression fittings or preferably soldered nipples, with a flexible amoured 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.In some cases it is necessary to have a number of fuel tanks in order to achieve the required operating range. In such cases, where possible, one tank should be regarded as the main tank for each engine and the other tanks should be arranged so that they will drain into the main tank by gravity. If a gravity system is not possible, then the system shown in Figure (C) should be used.Figure (C) shows a collector tank, fed by all the storage tanks and connected to the engine feed and return systems, but with a vent pipe taken to any convenient tank.There is a no doubt however, that a simple fuel system as illustrated in Figure (A) should be used wherever possible, as having a completely separate tank and supply to each engine guarantees that if an engine stops, due to running out of fuel or to water or foreign matter in the fuel, the other engine will not be affected simultaneously. This will give some time for appropriate manoeuvring action to be taken. The simple system will also require the minimum number of valves and fittings, which ensures maximum reliability in service.