Background

This product was designed with the intention of solving the biggest problem most guys encounter when they upgrade the fuel pump on their truck: fuel pump starvation from fuel sloshing.

A surge tank is usually a separate fuel tank fed by the main tank with the sole purpose of keeping the main fuel pump and pump pickup completely submerged to prevent a disruption in fuel flow. If fuel flow is disrupted it will result in a loss of fuel pressure to the engine which can easily cause engine damage from a lean condition. The AFP Surge Tank puts the surge tank inside of the main fuel tank so there is no need for external feed and return lines between the main and secondary surge tanks.

Fuel Tank

There is no modification necessary to the main fuel tank except for mounting the fuel level sensor (optional). This is compatible with the 04+ “returnless” fuel tanks that have the larger 5” opening. The 99-02/03 “return style” tanks have a smaller opening (~3”) and must be swapped out for a later tank for this to be installed. A compatible fuel tank is generally easy to find at any local salvage yard. If you need to upgrade your tank make sure you get one from the same body style and bed length of your current truck. For instance if you have a regular cab short bed truck, you need the short bed (5’9″) fuel tank. A tank from an extended cab or long bed will not fit as it its longer in the front and will hit the cab. You will also need the fuel filler hose that goes to the filler door from the newer tank as it is a different design.

Design

There are currently 3 versions of the AFP Surge Tank utilizing different fuel, pump configurations. There is a dual pump version utilizing 2x Walbro 450 or 525 pumps, a triple pump version utilizing 3x Walbro 450 or 525 pumps, and a version for the Aeromotive in-tank brushless pumps. The versions with the Walbro pumps will include the pumps, however the Aeromotive version will not include the large pump, it will only include the tank and fill pump. Currently all versions utilize a Walbro 255 as the fill pump to keep the surge tank full. The compatible Aeromotive pumps are for their “universal” kit which means you have to trim the inlet tube yourself (only difference to the vehicle or cell specific kits).

The AFP Surge Tank is made from 6061 aluminum and is compatible with all fuels. The surge tank is secured to the factory tank utilizing the stock tank Oring and top locking ring. All welds are TIG welded as needed. The top and bottom pieces are laser cut for the highest accuracy and best finish possible. The joining hardware is 304 stainless. For the dual and triple Walbro pump versions the pumps are suspended from the top via an aluminum rod and held in place by 2 laser cut holders and stainless clamps. The fuel hoses are corrugated plastic so there is no risk of leaks as with rubber (even the fancy 30R10 rated stuff) hose. The pump outlets are joined to a single -8AN ORB (for dual pumps) or -10AN ORB (for triple pumps) outlet via a custom billet bulkhead fitting. The return fitting for all versions is a -8AN and has a elongated return tube to prevent aeration in the surge tank by excessive fuel splashing. The vent has both rollover and splash prevention features by using both an internal floating and sinking ball and has a – 6AN connection at the top. In the event of a vehicle rollover or overfilling the tank the vent will be plugged to prevent fuel from spilling out.

Performance

There are a series of performance charts as part of the larger PDF (see link below). The basic performance can be summarized in the table below based on the different configurations:

The “seconds at WOT” would be the amount of time until the tank is drained at that power level, typically relating to a 1/4 or 1/8 race ET. For example with a triple 450 setup there is approximately 20 seconds worth of fuel available at 1800rwhp on gas, so as long as your 1/4 mile time is less than 20 seconds you are good to go. 20 seconds is a loooooong time at 1800rwhp short of any sort of standing mile racing. Please see the PDF and youtube video for additional information.

Wiring Harness

Optional with the surge tank will be a wiring harness with appropriately sized 8ga wiring for the power leads to the pumps, a 6ga ground lead, and electrical terminals for the wiring to the surge tank and relays. In the case of the triple walbro 525 setup, the combined current from all pumps at 80psi is close to 70amps! This is not insignificant. The wiring kit will contain 3x 80amp relays along with 3x 15ft runs of 8ga GXL wiring (red, orange). GXL wiring has a thicker coating than the common TXL wire used mainly for ECUs. The shorter 6ga ground wire should be run directly to a clean spot on the frame and secured with a bolt or self-tapping screw. Having the “big 3” electrical upgrade is recommended (0ga or better from battery NEG to frame, alternator to battery POS, and engine block to frame). There will also be 3x 15ft (black, yellow, and pink) runs of 18ga wire for activation of the relay.

For more information, please see my PDF HERE