Radium FHST-RA Fuel Hanger Surge Tank | BMW E90 E91 E92 E93 N54 N55 (20-1970 / 20-1972)

The E9X saddle bag tank sloshes under lateral load, and the OEM pump goes hungry exactly when you need it not to.

The Radium Engineering FHST-RA fuel hanger surge tank for the BMW E90, E91, E92, and E93 installs inside the fuel tank on the opposite side of the factory pump and holds one or two high flow aftermarket pumps. The OEM pump is retained and repurposed as a lift pump that fills the surge tank, while the pumps inside the FHST feed the engine. No permanent modification, no cutting the sheet metal, and full E85 compatibility.

Choose Your Version

• Fits Walbro GSS342 / AEM 50-1000 / AEM 50-1200 (20-1970)
• Fits Walbro F90000267 / 274 / 285 (20-1972)

What You'll Feel

• Fuel pressure that holds through sustained lateral G where the stock tank starves
• Capacity for one or two aftermarket pumps as power climbs
• Tool-less fuel pressure adjustment by knob, roughly 1psi per detent
• A vacuum reference port that swivels 360 degrees and seals on double O-rings
• A reversible install that leaves the tank and body untouched

Features

• Permits 1 or 2 surge pumps; pumps not included
• Integrated RA-series regulator with 1:1 adjustment and haptic detents
• Integrated 1-way fill valve and fuel starvation protection
• 8AN ORB feed port with preinstalled low profile 8AN male fitting to clear the OEM pump cover plate
• Four interchangeable 10-32 vacuum port fittings: 3/16in barb, 3AN male, push-to-connect for 1/4in tubing, and a vacuum plug for constant pressure
• Stainless electrical studs with nonconductive acorn nuts, ETFE insulated in-tank wiring
• Anodized aluminum construction, gasoline and ethanol compliant

The Details

The surge tank pumps draw from three sources: the OEM lift pump, the fuel pressure regulator return, and the integrated one-way fill valve, which is what keeps the tank full even when the main tank is sloshing. Note that the FHST eliminates the OEM post pump filter, so a low micron filter must be added separately; the 20-0475 fuel hanger feed kit is the matching solution. Wiring covers one surge pump with a relay, fuse, and hardware included, so a second pump needs a Radium 17-0031 DIY wiring kit. If you would rather run an engine bay regulator with a return line, the 20-0806 FPR block-off converts the built-in dead-head regulator to a return style system.

Kit Includes

• Fuel hanger surge tank, partially assembled
• Hardware to install one or two pumps
• Filter socks
• DIY fuel pump wiring kit for 1 pump, with relay and fuse
• Electrical parts kit for external wiring
• NOT included: fuel pumps and post pump fuel filter

Applications

• BMW E90, E91, E92, and E93 3-series with the N54 or N55 engine

Important Notes

• NOT compatible with BMW 1-series (E81, E82, E86, E87)
• Fits the E90/91/92/93 M3 fuel tank, but the M3's brushless pump means the installer must devise a way to trigger the surge tank pumps; this is not covered in Radium's instructions. The 20-0475 feed kit does not fit the M3 at all due to the exhaust system.
• A low micron post pump filter is required separately since the FHST removes the OEM unit