Dual Fuel & Long Range Tank Setup Schematic September 02 2015
Duel Fuel and Long Range Tank Setup
The popularity of twin tank systems is on the rise with more 4WD users running long range tanks and many people switching to green fuels such as biodiesel and vegetable oil conversions. When running twin tanks a six port valve, capable of switching both engine supply and return lines is of great importance. This acts to 1) prevent tank overflows associated with too much return fuel coming back to an already full tank and 2) prevent contamination between the tanks, particularly important in dual fuel systems. The key component to managing such a set up is the tank selector valve. Scintex supplies the Pollak 6 port valve and it considered the gold standard for such applications. Made in the USA and an OEM product on many vehicles, it is a trusted and reliable unit. Being sealed and water proof it is great for 4WD and 4x4 applications. The valve works by having a single output line to the engine and a single return line from the engine. It then runs dual in and out lines, one for each tank. When voltage is applied to the valve the motor will change the valve positions, switching both supply and return lines for each tank. This negates having to run twin supply and return lines to your engine from the valve. To trigger a change in valve position a DPDT On-On switch is required and is often dash mounted. Of key importance when installing a fuel valve is running appropriate filtration. Being a precise piece of automotive equipment the gear tolerances are minimal and any particulate matter such as rust from fuel tanks can build up and cause a failure. It is highly recommended that inline filtration be used on all lines supplying fuel to the fuel changeover valve. In the schematic below the fuel valve is shown in two halves to show how the supply and return lines work. It also aids to visualise how the systems can be set up with 3 port valves. The diagram shows the standard set up and plumbing diagram for a Dual fuel system, however can be applied to running long range tanks. In the case of long range fuel tanks, ignore the oil booster pump, heat exchanger, temperature controller and pad heater. The heated oil filter should be substituted with a standard fuel filter. These are all items required for dual fuels, in particular straight oil conversions, where the oil needs to be up to temperature so it has the viscosity of diesel before injection.