Radium - Fuel Hanger Surge Tank, BMW E90/E91/E92/E93

The Radium Fuel Hanger Surge Tank is a revolutionary way to eliminate fuel starvation that can occur during high performance driving, while also providing a way to upgrade the fuel pumps for high-horsepower engine modifications. This system installs inside the BMW fuel tank on the opposite side of the factory fuel pump and can hold one or two high-flow aftermarket fuel pumps. The OEM fuel pump is used to pump fuel into the FHST, while the pumps inside the FHST supply fuel to the engine. The system is E85 compatible and does not require any permanent modifications for installation.

HOW THE FHST WORKS

The OEM saddle bag fuel tank is quite complex. The venturi jet pump is driven by the feed line instead of the return (M3 has 2 venturi jet pumps). The post pump filter and FPR are integrated into the LH side of the tank where the FHST mounts.

When these BMWs experience high lateral G-forces, they can suffer from fuel slosh. The FHST is the best solution in preventing fuel starvation. The FHST pump(s) are supplied with fuel from 3 different sources:

• The OEM electric "lift" pump
• The fuel pressure regulator (FPR)
• The integrated 1-way fill valve

REGULATOR

RA-series regulators feature the first tool-less pressure adjustment. A jam nut and set screw are no longer required. With a simple turn of the knob, pressure will be increased or decreased. Additionally, there are no inherent air (vacuum/boost) leaks through the threads that traditionally a smoke detector would pick up. To aid in adjusting pressure, there are incremental detents that provide haptic feedback to the user. Every detent permits 1psi (+/-0.5psi) of adjustment depending on current fuel pressure. Furthermore, RA-series regulators feature a 360 degree swiveling vacuum reference port that is double O-ring sealed. This is the first in the industry. It permits the installer to quickly point the vacuum fitting in any direction with no tools required.

There are 4 interchangeable 10-32 threaded vacuum port fittings provided to cover all scenarios.

• Barbed Fitting: A black zinc-plated 3/16" (5mm) barb machined from high strength steel that is compatible with the following vacuum hoses: 5/32" (4mm), 3/16" (5mm), and 7/32" (6mm)
• 3AN Male Fitting: A black zinc-plated adapter machined from high strength steel that is compatible with 3AN hose ends
• Push-To-Connect: A nickel-plated brass fitting with Buna-N O-rings that is compatible with hard plastic 1/4" OD tubing
• Vacuum Plug: A black oxide stainless steel screw that is used to maintain a constant (non dynamic) fuel pressure. Beginning in the mid 1990s, vehicle manufacturers started transitioning to returnless fuel systems to lower EVAP emissions. To keep temperatures lower, these regulators are mounted inside the tank and do NOT have the ability to be vacuum referenced. This plug would be required in this scenario.

PORT AND FITTINGS

To clear the OEM fuel pump cover plate, the 8AN ORB threaded feed port features a preinstalled low profile 8AN male fitting.

ELECTRICAL

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 circuiting. Electrical hardware is included for the fuel pump(s) and OEM level sender. The in-tank wiring is insulated with high quality chemically resistant ETFE.

These kits include 1 relay, 1 fuse, and all associated wiring and hardware to install 1 surge tank pump. If an extra fuel pump will be installed, purchase a Radium 17-0031 DIY Wiring Kit HERE.

20-1970 FHST-RA BMW E90/91/92/93 Fits Walbro GSS342 or AEM 50-1200

This hanger will come partially assembled. It will include enough components to install one or two pumps into the surge tank. Pumps are not included.

20-1972 FHST-RA BMW E90/91/92/93 Fits Walbro F90000267/274/285

This hanger will come partially assembled. It will include enough components to install one or two pumps into the surge tank. Pumps are not included.

20-0475-03 Fuel Hanger Feed BMW E90/91/92/93 Stainless Filter

NOTE: Because of the exhaust system, these fuel feed kits are NOT compatible with the M3.

An 8AN PTFE fuel feed line secures to the FHST outlet, as shown below. The fuel line clears the OEM fuel pump cover and all suspension related parts. No cutting or drilling is required. The PTFE hose is routed underneath the vehicle and sent to a Radium Engineering fuel filter secured to the body using OEM hardware. From there, a SAE quick connect fitting is provided to reattach the OEM N54/N55 fuel line.

20-0475-05 Fuel Hanger Feed BMW E90/91/92/93 Microglass Filter

NOTE: Because of the exhaust system, these fuel feed kits are NOT compatible with the M3.

An 8AN PTFE fuel feed line secures to the FHST outlet, as shown below. The fuel line clears the OEM fuel pump cover and all suspension related parts. No cutting or drilling is required. The PTFE hose is routed underneath the vehicle and sent to a Radium Engineering fuel filter secured to the body using OEM hardware. From there, a SAE quick connect fitting is provided to reattach the OEM N54/N55 fuel line.

20-0806 Fuel Hanger FPR Block Off

The BMW E9X FHST can be converted from a built-in regulator dead-head system to a return style system using this kit. For users wanting to run an engine bay mounted regulator with a return line back to the tank, this kit makes that possible. The parts in the kit disable the built-in regulator allowing the use of an external regulator elsewhere in the system. The hanger top plate features a return port that can be used for the return line from the external regulator.

NOTES

• A 6AN ORB fitting is required for the return port in order to attach a hose. Keep in mind, this fitting must be low profile (20-1000-0606 shown below).
• A fuel pressure regulator (not included) must be installed downstream in the system. This procedure is not discussed in the instructions.
• Early models of the FHST without a return port in the top are not compatible with this kit.