Fuel select valves

In twin-tank systems where diesel fuel is used to start the engine and vegetable oil is used when the vehicle is warm, one or more fuel selector valves are required to manage which fuel is used at any given time.

The valves can be operated manually or electrically via one or more switches. BioTuning offer a range of solenoid 3/2 way solenoid valves specifically for use in vegetable oil conversions. The valves we offer are compared here.

BioTuning Fuel Selector Valves

Schemtic diagram of the BioTuning vegoil conversion system layoutDiesel engines have two fuel lines between the engine and the fuel tank. The fuel supply and return. The fuel pump supplies the engine with much more fuel than it requires. The engine burns maybe 5% of the fuel and returns the rest to the fuel tank.

When running the engine with two fuels, the minimum requirement is to use a single 3 way fuel selector to choose which fuel tank the fuel is drawn from. The returned fuel can be 'looped' back into the engine. Using a single valve is not ideal for a number of reasons;

1. Pockets of air may get trapped in the fuel lines and won't get released, causing damage to the injector pump (IP) and fuel system.

2. The purge cycle (flushing the vegetable oil with diesel) will take a long time. Rather than flushing out the vegetable oil with diesel, it is gradually replaced with diesel as it is burned by the engine.

It is much better to use a pair of 3 way fuel selector valves to avoid these problems.

Solenoid valves are electromagnetic 3 port selector valves that are used to switch between two fuel tanks. The valve selects from one port when power is supplied to the valve (energised) and from the other port when it is not powered (unenergised). Two fuel selector valves enable you to control the supply and return of fuel. It is possible to use a single 3 position switch to control the valves in a way that draws fuel and returns it to the same tank in two of the positions, replicating the standard system before modification but now allowing you to run on diesel with the switch in one position or vegoil with it in another. The third switch position gives a quick purge to flush out the vegoil with diesel. This is our preferred means of operating a twin tank kit and you will find options for controlling valves in this way in our kits and fuel select valves pages.

BioTuning have a range of solenoid valves that are suitable for conversions for many different sizes of diesel engine. We currently have one valve in our range. The VSV8, we are unable to source the VSV12 and the Pevekoil valves so sadly these are now retired. See below for pictures of the valves, side-by-side, in various stages of disassembly.

Photo VSV8 VSV12 Pevekoil
SuitabilitySmall engined diesel cars and vans (eg 1.9TDi)Larger engined diesels (eg. 4x4s, pickups, commercials)Larger engined diesels (eg. 4x4s, pickups, commercials)
Internal bore
Body material
Brass/ stainless steel
Anodised aluminium / stainless steel
Aluminium/ stainless steel
Coil options
12v DC
12v DC, 24v DC
12v DC, 24v DC
Viton Viton
Threads 2 x female 1/4" BSP
1 x male 1/8" BSP
3 x female 1/2" BSP 3 x female 3/8" BSP
Hose tail options 6mm or 8mm 8mm or 10mm 8mm or 10mm
Seal kits available No Yes No
Serviceability Easy but requires removal of the top hose tail Very easy and without removal of hose tails Very easy and without removal of hose tails
Connector block Clear with LED power indicator Clear with LED power indicator Black

BioTuning Valves Compared (a)BioTuning Valves Compared (b)BioTuning Valves Compared (c)BioTuning Valves Compared (d)BioTuning Valves Compared (e)BioTuning Valves Compared (f)BioTuning ValvesCompared (h)BioTuning Valves Compared (g)

Alternative options

Pollak Valve - motorised valve with strong pedigree in vegoil conversions. Be sure to buy a genuine valve since there are many fakes on the market which soon fail when used with vegoil whereas the genuine valves are vegoil approved.

Tecalemit solenoid valves, very highly regarded by the early vegoil converters. 4mm internal bore. OEM for thirsty Jaguars and Daimlers with their twin petrol tanks but production ceased in 2009 when the original OEM use declined.

Manual fuel select valve from a Land Rover

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