Video: Holley Introduces an In-Tank Fuel Pump for Carburetors

Above left: This exploded view of the fuel pump shows Holley’s diecast aluminum in-tank fuel pump module hanger bracket (top left). The module hanger minimizes pump vibration, and it is a low-profile design (only 1.275-inches above the tank mounting surface) to fit in tight spaces.

Holley has introduced a 255-liter per hour in-tank fuel pump module (part no. 12-129) that operates with the low-pressure demands of carbureted engines. The OEMs have been using in-tank fuel pump modules with fuel injection for years, so why did Holley develop one for carburetors? In the past, enthusiasts bolted on an external Holley red or blue pump, and they worked (still work) great, however, Holley’s new aluminum diecast in-tank module design takes advantage of the development of in-tank fuel pump technology.

The Holley in-tank module allows for quiet operation (in comparison to an external electric fuel pump), and the pump is much more efficient as a pusher rather than suction pump-type. The pump being in the tank also reduces the chances of drawing air into the fuel system, because the pump pickup is located at the bottom of the tank constantly submerged in the fuel.

The module has a diecast pump hanger bracket that minimizes pump vibration, and the low-profile design (only 1.275-inches above the tank mounting surface) fits where space is limited. To be ready to hit the streets, simply mount the pump module, connect the fuel line, and supply a 12-volt source and ground. Holley recommends the use of their 30-amp fuel pump relay (part no. 12-753) and a minimum of 12-gauge wires for a trouble-free installation.

Above left: The return-less Holley fuel pump has an outlet port and a vent port. The fuel lines are connected to the ports. Add a 12-volt source and ground, and the pump will be operational. Above center: The underside of the aluminum diecast in-tank pump module is where the internal regulator is located. The regulator limits the fuel pressure to 6 psig, and if necessary, the regulator can be swapped if a high-pressure EFI system is installed on the engine. Above right: Holley recommends the use of their 30-amp fuel pump relay (part no. 12-753) and a minimum of 12-gauge wires for a trouble-free installation. The use of a relay will ensure the pump receives battery voltage regardless of the loads on the electrical system.

Holley claims support up to 700 horsepower (carbureted) with the internal regulator factory set at 6 psig with 13.5-volts and a 10.4-amp draw. The in-tank fuel pump module is upgradable. With a simple swap of the internal regulator in the pump module, the fuel pressure can be increased to operate with electronic fuel injection (EFI) systems.

The expandability of the Holley in-tank pump module will allow you to build that carbureted engine that can be upgraded to EFI in the future. For instance, you install a 5.7L Hemi into your a-body Mopar. For now, a carburetor or two on a carburetor intake manifold will get the job done. With the carburetors plumbed and an MSD 6-HEMI controller ignition timing system (sold separately) handling the spark, the Hemi will run well.

Then when money frees up, you can install the EFI unit of your choice for the Hemi (along with the matching wiring harness) and with a swap of the fuel pump’s internal regulator, the fuel pressure is sustained at a pressure for a late-model EFI system.  For more information about Holley’s new in-tank fuel pump or any of their products, contact them at

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Chris Holley

Technical Contributor Chris has been a college professor for 26 years; at Pennsylvania College of Technology in Williamsport, PA. for the last 21 years. Chris instructs automotive classes in HVAC, electrical/electronics, and high-performance, including using a chassis dyno, flow benches, and various machining equipment. Recently, he added a vintage vehicle upholstery class to his teaching assignments. Chris owns a '67 Dart, a '75 Dart, a '06 Charger, and a '12 Cummins turbo diesel Ram, and he is a multi-time track champion (drag racing) with his '69 340 Dart, which he has owned for 35 years.

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