How To Install A Holley In-Tank Retro-Fit Fuel Module Kit Into Your OEM Fuel Tank

Holley's In-Tank Retro-Fit Fuel Module Kit consists of three major components. The first component is the fuel pump hanger assembly, which contains the inlet, outlet, and vent line fittings and also serves as the foundation for mounting the fuel pump. Its modular design keeps things streamlined so that the assembly fits where space is at a premium, while its innovative clamping system allows the unit to rotate 360-degrees for flexible plumbing and wiring routing options.

The fuel pump attaches to the fuel pump hanger assembly via a pair of clamps by using a billet bracket designed to control pump vibration while also providing a low profile design. Holley offers Retro-Fit fuel modules with a 255LPH pump, 340LPH pump, 450LPH pump, and a 525LPH pump, the larger of which is good to support 1,200 horsepower on EFI or 1,450 horsepower with a carburetor.

The third component and one of the items that makes the Retro-Fit Fuel Module Kit so unique is Holley's proprietary fuel pickup design called HydraMat. Race proven on the track and on the street, Holley's HydraMat fuel reservoir system is designed to maintain adequate fueling during the most aggressive starting, stopping, and hard cornering. Surface tension and fluid wicking are the secrets of the HydraMat’s ability to draw fuel from nearly any area that has contact with fuel and store it in the internal reservoir, eliminating the need for special pickups or internal baffling to provide adequate fuel delivery in any circumstance. Available in a myriad of sizes, the HydraMat that comes as standard with the Retro-Fit Fuel Module is 3x15-inches and features six clocking pin locations to allow for 360-degree adjustment to clear fuel level sending units or any tank floor restrictions.

The first step to installing the fuel module is to choose a location on your gas tank that's going to have the least amount of interference. Internal baffling and fuel level senders need to be avoided for best results. Clearance between the floor of the vehicle and the fuel tank should also be taken into consideration due to the pump hanger assembly's thickness (1.275-inches). Once the location is chosen, a 3 1/4-inch hole will need to be cut into the tank using a hole-saw.

Once the hole is cut, the depth of the tank is measured, noted, and compared with a set of specifications provided by Holley. While our tank is relatively shallow, the Retro-Fit Fuel Module is compatible with tank depths from 7 1/2 to 12-inches, fitting a large variety of applications

These specs will determine the amount of material to be removed from the fuel pump inlet...

...as well as the billet fuel pump mounting bracket.

Once the billet fuel pump mounting bracket has been trimmed, it's installed on the fuel pump hanger assembly using two screws and lock washers. Here, the innovative mounting design is visible on the underside of the hanger assembly. As each screw is tightened, the aluminum lugs rotate into position and draw the assembly in tight to the top of the tank.

Next, the fuel pump inlet hose is attached to the hanger assembly before the pump is snugly tightened to the fuel pump mounting bracket. The wiring connection is then made while being mindful not to pinch any of the wires in the assembly.

The HydraMat snaps in place on the bottom of the fuel pump and can be easily removed and reinstalled. Its design allows it to be installed in six different orientations in order to help avoid any internal obstacles.