Radium Engineering FHST-RA – BMW E90–E93 (Walbro / AEM Options)

The Radium Fuel Hanger Surge Tank (FHST) eliminates fuel starvation under high-performance driving while offering a solution for upgraded high-flow pumps. It installs on the opposite side of the factory pump and holds one or two aftermarket pumps. The OEM pump is repurposed as a lift pump to fill the FHST, and the FHST pumps feed the engine. No permanent vehicle modifications are required. Fully E85 compatible.

BMW FUEL TANK SETUP
The OEM saddle-style tank uses a venturi jet pump driven by the feed line. The post-pump filter and FPR are integrated on the LH side, where the FHST installs.

FUEL DELIVERY SYSTEM
Fuel is delivered to the FHST from three sources:

• OEM lift pump

• Integrated FPR return

• 1-way bottom valve

This multi-source system keeps the FHST full, even during aggressive driving. When the LH side of the tank is low, the lift pump and FPR continue supplying fuel.

INTEGRATED FUEL PRESSURE REGULATOR

• 1:1 vacuum-referenced or static fuel pressure

• 6-hole internal diverter reduces aeration

• Double O-ring swiveling vacuum port

• Four interchangeable vacuum port fittings:

  • Barbed Fitting (3/16" / 5mm)

  • 3AN Male Adapter

  • 1/4" Push-to-Connect

  • Vacuum Plug

PLUMBING
The 8AN ORB feed port includes a preinstalled low-profile 8AN male fitting to clear the factory pump cover.
Sock filters are used on the pump inlets. A post-pump fuel filter (not included) is recommended—see the 20-0475-0X kit.

ELECTRICAL

• Stainless electrical studs with acorn nuts

• ETFE in-tank wiring

• Pre-wired for 1 surge tank pump

• Includes relay, fuse, and install hardware

• For dual-pump setups, add Radium 17-0031 wiring kit

PUMP CONFIGURATION

P/N: 20-1970
Compatible with:

• Walbro GSS342

• AEM 50-1200

P/N: 20-1972
Compatible with:

• Walbro F90000267

• Walbro F90000274

• Walbro F90000285

FEATURES

• Drop-in OEM replacement

• Supports 1 or 2 surge pumps

• Integrated 1:1 adjustable FPR

• Surge tank with 1-way fill valve

• Anodized aluminum construction

• 8AN ORB outlet

• Stainless and fuel-resistant components

• Includes relay(s) and fuse(s)

• Fully E85 compatible

COMPATIBILITY
BMW E90 3-series (N54 or N55)
BMW E91 3-series (N54 or N55)
BMW E92 3-series (N54 or N55)
BMW E93 3-series (N54 or N55)

NOTES:

1. Compatible with the E90/91/92/93 M3 fuel tank. However, because the M3 uses a brushless fuel pump, a solution must be devised for triggering the new surge tank fuel pump(s).

2. Not compatible with BMW 1-series vehicles (E81/E82/E86/E87).