The Radium Engineering FHST (fuel hanger surge tank) is the ultimate solution for fuel starvation issues. Fuel slosh is common when driven aggressively. Unstable pressure resulting in a lean fuel mixture can cause engine damage. A stand-alone surge tank is an excellent device for eliminating fuel starvation, but installation can be complex. The FHST is a fully functional fuel surge tank mounted inside the OEM tank. It can be configured with 1, 2, or 3 high pressure pumps and 1 lift pump to meet the fuel demands of any power level.
Even with all of the extra fuel pumps, the FHST system is very straight forward and relatively simple to install. No grinding, bending, or modification of the vehicle is required. Furthermore, the system is compatible with all alternative fuels such as E85.
FUEL SURGE TANK
What keeps the surge tank full? The FST pump(s) are supplied with fuel from 3 different sources: the high flow (low pressure) lift pump, the fuel pressure regulator (FPR) return, and the two integrated 1-way fill valves.
1. A stainless steel collector box is provided that secures to the fuel tank floor. The sensors and lift pump attach to this box assembly.
The collector box features a 1-way trap door to control slosh and prevent lift pump starvation. The lift pump sends fuel into the lower portion of the surge tank.
Intricate machining is used to keep fuel moving tangentially into the surge tank. This laminar flow prevents foaming and aeration.
2. The returning fuel from the FPR also fills the surge tank.
As shown above, this returning fuel is routed through a diverging deflector to prevent foaming and aeration.
3. Lastly there are two 1-way fill valves integrated into the lower portion of the surge tank.
They allow fuel in, but not out. They supply 355LPH each (710LPH total).
PLUMBING
The preinstalled barb fittings permit direct connections to the factory fuel hoses. No extra fuel plumbing is required.
Additionally, 8AN (feed) and 6AN (return) adapter fittings are provided for connecting aftermarket -AN style hoses. The fitting ports are machined low enough to clear the unibody sheet metal. 
FUEL PUMP INFORMATION
All kits come partially assembled with the final assembly performed by the technician during installation. There will have enough parts to run 1, 2, or 3 surge tank pumps and 1 lift pump. The user must supply their own compatible fuel pumps. Refer to the instructions above for more details.
ELECTRICAL
Bulkheads:
The custom designed stainless steel 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. Enough studs are built in the top hat to accommodate the lift pump as well as 3 surge pumps (including brushless).
External Wiring:
Because the fuel "lift" pump supplying the FHST (in the original pump location) will now operate at very low pressure (high flow), the OEM external fuel pump wiring will be sufficient for the lift pump.
High current fuel pump wiring is provided for installing one FHST pump (1 relay, 1 fuse, and all associated wiring and hardware). NOTE: To wire in additional FHST pumps, extra fuses and relays are required.
Sensors:
Because the factory fuel level sensor is integrated into the OEM sender, a replacement fuel level sensor is provided. This new OEM Nissan sensor has the correct resistance range to work the gauge cluster properly. The original low fuel switch is reused.
Chemical Compatibility:
All in-tank wiring is insulated with chemically resistant ETFE. Electrical hardware is included for the fuel pump(s) and sensors.
FEATURES
-Drop-In Installation
-Anodized Aluminum Construction
-Merged 8AN ORB Female Pump-Out Port
-8AN ORB Female Return Port
-Permits up to 4 Pumps Total
-Compatible with up to 3 Brushless Pumps
-High Current Electrical Hardware
-Stainless Steel Hardware and Clamps
-Gasoline, Methanol, and E85 Compliant