Radium FCST-X, 2 Surge Pumps and 1 Lift Pump Included, Walbro GSS342 - 20-1990-02

LEGACY FCST FEATURES
The features listed below carry over from previous fuel cell surge tanks.
-Merged single 10AN ORB female threaded outlet. All pumps use check valves that prevent back-flow.
-One-way fill valves (355LPH each) allows fuel in, but not out, keeping the surge tank full.
-Multiple fuel pump options including gerotor, reaction turbine, and brushless DC motor pumps.
-Hermetically sealed high-current stainless steel electrical studs capable of handling all pumps.
-Simplified servicing eliminates sealing washers and fuel cell retaining brackets.
-Full CNC aluminum construction with anodized surfacing for superior corrosion resistance.
-Fuel compatibility: leaded and unleaded gasoline, methanol, ethanol, E85, etc.
-Optional fuel surge tank level switch and diagnostic LED failsafe port.
-Rollover vent valve protection 

NEW FEATURES
In addition to all previous FCST features, the new FCST-X rendition is packed with innovations.
-Fast lift and surge pump access (9 bolts total)
-Integrated lift handle for fuel pump servicing
-Lightweight surge tank increased from 2.2L to 2.6L
-Compatible with up to 4 brushless fuel pumps
-Up to 4 Bosch BR540 fuel pumps (DW400) 
-Up to 3 Ti Automotive E5LM brushless pumps
-Up to 4 brushless Bosch pumps (DW440)
-Compatible with 16AN inlet mechanical pumps
-Easily swappable pump modules (sold separately)
-Compatible with shrouded level sensors
-Designed with less potential leak points
-Improved fluid control for quick filling
-Optimized internal fluid management
-Enhanced roll over protection
-Anti-rotation electrical terminals

COMPATIBLE WITH MY FUEL CELL?
To install a Radium Engineering FCST-X into a fuel cell, the following criteria must be met:
1. The fuel cell must have the industry standard 6"x10", 24-bolt flange opening.
2. The opening must be on the top face of the fuel cell (i.e. not a side face).
3. The cell depth must be at least 7.7" (196mm) measured from the outer top face to the internal bottom face.

HOW IT WORKS
A lift pump scavenges fuel from the bottom of the fuel cell and pumps it into the 2L surge tank. Inside the surge tank canister, up to 3 EFI fuel pumps can be used to feed high pressure fuel to the engine. As shown below, fuel cannot pass between the 3 independent filtration chambers (A, B, C). If less than 3 pumps are installed, the empty port does NOT need to blocked off.

If the lift pump starves, the volume inside the surge tank canister will keep the surge tank pumps fed and the engine supplied with fuel. The return from the fuel pressure regulator is also routed to the surge tank canister to help keep it full.

There are 3 fill valves integrated to the bottom of the surge tank. These 1-way FKM fill valves are sealed shut unless the fuel level in the cell rises above the fuel level in the surge tank. If this happens, each fill valve opens and sends 355LPH of fuel (1065LPH total) into the surge tank until fuel level reaches an equilibrium. 

Excess fuel in the surge tank simply overflows back into the fuel cell. This dynamic sequence is all done inside the safety of a fuel cell.