OVERVIEW

A fuel surge tank (FST) is designed to prevent fuel starvation on vehicles with inadequate fuel tank baffling. Fuel is supplied to the surge tank by a lift pump, which in most cases is the OEM in-tank fuel pump. The volume of fuel inside the surge tank acts as a buffer to always keep the FST pump(s) supplied with fuel, even if the lift pump starves momentarily.

This volume is maintained by the lift pump as well as the fuel returning from the built-in fuel pressure regulator. Excess fuel in the surge tank is returned back to the vehicle's main fuel tank. The surge tank also provides a quick and easy way to upgrade any standard fuel system without opening the stock fuel tank. This is an excellent fueling solution for vehicles installing large demand power upgrades such as forced induction.

The Radium Engineering MPFST-R is the perfect solution for simplifying a high power vehicle experiencing fuel starvation during aggressive driving. When compared to a typical surge tank, there is one less port fitting. Instead, the built-in regulator returns low pressure fuel directly into the surge tank negating the need for an external FPR return line

The MPFST-R will accept 1, 2, or 3 fuel pumps. Refer to the pump compatibility section of each individual unit below to see a list of compatible pumps for each.

PLUMBING & PORTS

All pumps feed out through the single outlet port from the integrated fuel pressure regulator. This single feed line will dead-end at the engine (no return line). This "PUMP OUTLET" port is a 10AN ORB female and comes preassembled with an adapter fitting for 8AN male. Other adapter fittings can be installed as needed (sold separately).

The 'OVERFLOW' and 'SUPPLY' ports are female 8AN ORB threaded and come preinstalled with -6AN male adapter fittings. These adapter fittings can be swapped out with different sizes (sold separately).

For cars without a return port on the fuel tank, one must be created. This port can not be capped off. See the technical data sheet on the right for more information on creating a return port.

ELECTRICAL

The fuel pump power connections are handled with specially designed anti-rotation high-current electrical studs. Necessary ring terminals and hardware are included with every surge tank. All internal wires are gasoline, ethanol, and methanol compliant.

MOUNTING

Integrated mounting feet are designed to be used with M6 (or 1/4") fasteners.

BUILT-IN 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.

To aid in adjusting pressure, there are incremental detents that provide haptic feedback to the user. Every detent equates to about 1psi 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.

The MPFST-R features an 1/8" NPT fuel pressure port at the regulator. An 1/8" plug is provided, or a fuel pressure gauge or sensor can be installed to adjust and monitor fuel pressure.

The built-in regulator is 1:1 vacuum reference capable. There are 4 interchangeable 10-32 threaded vacuum port fittings provided to suit different vacuum hose types. The reference port can also be plugged with the included screw for constant fuel pressure.

	20-1445 MPFST-R, PUMPS NOT INCLUDED, WALBRO GSS342 OR AEM 50-1200 OR DW440 This MPFST-R allows the installation of 1, 2, or 3 of the pumps listed below. It will include all necessary parts to install the pumps into the surge tank except for the pump(s) themselves. PUMP COMPATIBILITY Walbro GSS342 AEM 50-1200 Deatschwerks DW440 More compatible pumps are possible that are not listed here. Any pump that matches the same physical package can be installed as well.
	20-1446 MPFST-R, PUMPS NOT INCLUDED, BOSCH BR540 OR DW400 This MPFST-R will allows the installation 1, 2, or 3 of the pumps listed below. It will include all necessary parts to install the pumps into the surge tank except for the pump(s) themselves. PUMP COMPATIBILITY Deatschwerks DW400 Bosch BR540⁽¹⁾ ⁽¹⁾These pumps do not feature a check valve. Use only as the primary pump in a staged pump installation. NOTES The physical size of these pumps will cause an interference with the optional fuel level switch in one of the installation positions. For this reason, only 2 pumps can be installed in this surge tank when using the level switch.
	20-1447 MPFST-R, PUMPS NOT INCLUDED, WALBRO F90000267/274/285 This MPFST-R allows the installation 1, 2, or 3 of the pumps listed below. It will include all necessary parts to install the pumps into the surge tank except for the pump(s) themselves. PUMP COMPATIBILITY Walbro F90000267 Walbro F90000274 Walbro F90000285 Walbro F90000295⁽¹⁾ Protec 11928⁽²⁾ Fuelab 49614⁽²⁾ Deatchwerks DW810⁽²⁾ ⁽¹⁾These pumps do not feature a check valve. Use only as the primary pump in a staged pump installation. ⁽²⁾To use the following brushless pumps, the 13-1187 TRIPLE PUMP BASE, 12MM INLET BRUSHLESS PUMPS must be purchased separately.
	OPTIONAL FUEL PRESSURE GAUGE To simplify fuel pressure regulator adjustments, the 0-100psi pressure gauge can be installed directly into the NPT port atop all MPFST-R models. This high-accuracy fuel pressure gauge is suitable for all fueling applications. It features an acrylic lens with a silicone filled dial that reads from 0 to 100psi (0 to 6.9 BAR) with +/- 2% accuracy. The silicone fluid prevents the needle from vibrating for easy pressure readings. The internal bubble is normal. Rugged stainless 1-5/8" OD steel case (1-3/4" OD bezel) with nickel plated male 1/8" NPT fitting. Available with black bezel and housing only. NOTES The internal silicone fluid bubble is normal Over pressurizing can permanently misalign the needle calibration PTFE thread sealant paste should always be used on NPT threads
	OPTIONAL FUEL LEVEL SWITCH This 1/8" NPT fuel level switch should be installed inside the container. When fuel level drops, a switched signal can be used many different purposes: Dashboard mounted indicator Programmable ECU input for safety purposes To turn ON/OFF the lift pump when applicable The level switch is constructed of corrosion resistant stainless steel compatible with all fuel types. It includes 24" long, 20AWG flying leads. NOTES Prior to installing, check the direction of the signal on a test bench Switch polarity can easily be reversed by removing the E-clip and flipping the float 1/8" NPT threaded port is required for installing Always apply PTFE thread sealant to tapered pipe threads The level switch is not compatible when installing 3 Bosch BR540 or 3 Deatschwerks DW400 pumps. These fuel pumps are too big and interfere.
	OPTIONAL FUEL LEVEL SWITCH W/DIAGNOSTIC INDICATOR The Fuel Level Diagnostic Indicator can be used as a visual reference for fuel level. When the fuel level switch is triggered, the signal is sent directly to this LED. While often impractical to be viewed while driving, this indicator can be used for diagnosing a potential fueling issue. NOTES A 2AN ORB (5/16"-24) threaded port is required for installing If stacking on top of the fuel level switch (as pictured above) the panel thickness must be 0.75" minimum Soldering is required The level switch is not compatible when installing 3 Bosch BR540 or 3 Deatschwerks DW400 pumps. These fuel pumps are too big and interfere.