Radium Fst-R, Pump Not Included

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  • Regular price $529.95

A fuel surge tank (FST) is designed to prevent fuel starvation to the engine on vehicles with inadequate fuel tank baffling. The FST fuel pump feeds the fuel rail(s). The volume of fuel inside the surge tank acts as a buffer to always keep the FST pump supplied with fuel. This volume is maintained by the main fuel tank's (lift) pump as well as the fuel returning from the fuel pressure regulator.

In the case of the FST-R, the regulator is built into the surge tank and recirculates fuel internally. Excess fuel in the surge tank is returned back to the vehicle's main fuel tank.

Installing a surge tank is also an easy way to upgrade the fuel pump of a vehicle without opening or modifying the OEM fuel tank. Need help selecting a fuel pump configuration for your vehicle? CLICK HERE for a unbiased test of popular fuel pumps.


The FST-R (Fuel Surge Tank–Regulated) houses a single internal fuel pump and has an integrated fuel pressure regulator machined into the top cap. This eliminates the need for an external fuel pressure regulator along with extra fittings and hoses. This simplifies the installation, reduces overall cost, reduces weight, and eliminates potential leak points in the fuel system. Furthermore, this system permits cooler fuel temperatures as the fuel is not returning from the hot engine bay.

The high-flow regulator is adjustable and features interchangeable orifice sizes with calculated flow diameters to match the fuel pump flow to the regulator. This added precision will resist diaphragm flutter and optimize pressure stability.

The screw on top of the regulator adjusts fuel pressure on the fly. A vacuum line can be installed on the barb to achieve a 1:1 vacuum reference. Note: returnless fuel systems commonly use a constant fuel pressure. In this case, the vacuum reference hose is not required.

All three ports are tapped to 9/16-18 (6AN ORB). Three 6AN adapters fittings are preinstalled to the ports. Additionally, one 6AN ORB fitting that adapts to 8AN male is provided, if needed. If using a fuel pump that does not have an integrated check valve (such as the brushless Ti Automotive E5LM), Radium 20-0534 can be screwed directly to the 8AN male adapter, as shown below. This picture below also has a Radium 14-0534 to adapt the check valve outlet from 10AN male to 8AN male.

The FST-R can be configured with all 39mm fuel pumps from many leading manufacturers.
Ti Automotive E5LM (brushless)
Walbro F90000267
Walbro F90000274
Walbro F90000285
Walbro GSS341
Walbro GSS342
AEM 50-1000
AEM 50-1200
1. There many compatible pump manufacturers not listed.
2. The FST-R is not available in dual-pump configurations.

The newly designed stainless electrical studs easily handle the high current demand that compact multi-pin bulkhead connectors lack. These serviceable connections are hermetically sealed and impervious to all standard and exotic fuels. Non conductive anodized aluminum acorn nuts are provided to prevent any accidental short circuiting. Electrical hardware is included for the fuel pump. Furthermore, the in-tank wiring is insulated with high quality chemically resistant ETFE. Relay kits, such as 17-0031, are recommended to drive these new internal fuel pump.

As shown above, the FST-R now features a built-in electrical strain relief for the fuel pump wires. Furthermore, a billet aluminum dust cap is provided to hide all external wires, as shown below.

The 2 ports on top are for fuel entering the FST-R (from the lift pump) and fuel overflowing and leaving the FST-R (to the main tank). They are interchangeable and now feature an internal flow deflector that prevents fuel foam and aeration.

The side port is the regulated pressure output and is plumbed directly to the engine. No additional fuel pressure regulator is required. However, a fuel pressure gauge/sensor is required to set and monitor fuel pressure. It can be located anywhere between the FST-R output line and the fuel rail(s).

As shown above, the Radium Engineering fuel pressure gauge is a simpley solution.


-Full CNC aluminum construction
-Anodized for compatibility with all fuel types
-Integrated adjustable FPR with 1:1 vacuum reference
-Interchangeable regulator orifice sizes to match pump flow
-Electrical strain relief with wiring dust cap
-Flow deflector to prevent foam and aeration
-6AN fittings including one 8AN (purchase others HERE)
-FKM O-ring sealed interfaces 
-Stainless steel hardware