Fuel Hanger Surge Tank - FD3S

The Radium Engineering fuel surge tank hanger permits the use of 1, 2, or 3 aftermarket high pressure pumps and 1 lift pump in the stock Mazda FD RX7 fuel tank. It is compatible with following models:

1993-1995 Mazda FD RX-7 (US)
1992-2002 Mazda FD RX-7 (JDM)

The unique integrated 1.85L surge tank completely eliminates fuel starvation. No grinding, bending, or modification of the trunk floor sheet metal is required. 

This system is compatible with the following fuel pumps:
Walbro F90000267/274/285

To simplify aftermarket -AN hose plumbing, the 10AN ORB threaded feed port features a low profile 8AN male fitting and the 8AN ORB threaded return port features a low profile 6AN male fitting. To reconnect the OEM feed and return hoses, barb fittings are also included.

The custom designed stainless electrical studs easily handle the high current demand that compact bulkhead connectors lack. These serviceable connections are properly sealed and impervious to all standard and exotic fuels. Nonconductive acorn nuts are provided to prevent any accidental short circuits. Furthermore, the high quality in-tank wiring is insulated with chemically resistant ETFE. Electrical hardware is included for the fuel pump(s), OEM level sender, and OEM temperature sensor.

Integrated Surge Tank
A fuel surge tank (FST) is the best solution in preventing fuel starvation. Because the FD RX7 can experience high lateral Gs, it inherently suffers from fuel slosh. Fortunately, Mazda manufactured a gas tank with a very large bolt flange pattern (similar to the FCST) permitting various upgrading options. 

For a proper FST to function, a lift pump is necessary to maintain volume within the surge tank. This lift pump is located in the rear portion of the OEM sub tank within the Mazda gas tank. Included in the kit is a lift pump mount that snaps onto 3 sides of the OEM sub tank. It also serves as a baffle keeping the lift pump supplied with fuel. Measures were taken to ensure that the lift pump always has fuel to deliver to the surge tank.

The 1" check ball allows fuel into this tight area during acceleration (above) and traps fuel in during deceleration (below). 

The lift pump sends low pressure (high volume) fuel in the FST through a special deflector in the bottom of the surge tank canister. The 24 hole diverter evenly disperses fuel inside the canister preventing air bubbles and foaming. When a low demand for fuel is present, the canister will overflow back into the OEM sub tank.

Pre pump filters are included for proper inlet filtration.

Because all compatible fuel pumps utilize check valves, the high pressure pump outlets merge into a single 10AN billet collector.
 
The returning low pressure fuel from the regulator is sent back into the FST keeping it full. A second 24 hole deflector is used in this location further preventing air bubbles and foaming. All of this happens inside the OEM gas tank.

Features
-Drop-In OEM Replacement
-Permits 1-3 Surge Pumps plus 1 Lift Pump 
-8AN Male Pump Outlet Fitting
-6AN Male Return Inlet Fitting
-Fuel Starvation Protection
-High Current Electrical Hardware
-Compatible with Various Pumps
-Anodized Aluminum Construction
-Gasoline and Ethanol Compliant
-Anodized Aluminum 8AN Male Fitting for Feed
-Anodized Aluminum 6AN Male Fitting for Return
-Anodized Aluminum 8.5mm Barb Hose Ends for OEM Feed/Return
-Anodized Aluminum Surge Tank Canister
-Anodized Aluminum OEM Fuel Sensor Mount
-Anodized Aluminum Lift Pump Baffle and Check Ball
-Fuel Resistant Submersible PTFE Tubing
-Fuel Resistant ETFE Insulated Wiring
-Stainless Electrical and Mounting Hardware
-Stainless Steel Mesh Triple Pump Filter