In-Tank Fuel Pumps

Can your stock fuel pump no longer deliver enough fuel after the engine has gained more power or higher boost pressure? An in-tank pump sits down in the tank, where the fuel typically cools it. It is for you if you are upgrading the fuel supply in your tuning project.

What does an in-tank fuel pump do?

The pump sits in the tank or in the original pump housing and pushes the fuel towards the engine. It does not have to suck the fuel through the line, so the risk of vapour bubbles is typically lower. The alternatives are inline fuel pumps mounted on the fuel line and mechanical fuel pumps driven by the engine. All types are collected under fuel pumps.

How to choose a pump

The category includes pumps from brands such as DeatschWerks, Aeromotive, Walbro, AEM and AMS. Choose based on these criteria:

• Flow: The pumps here range from 165 LPH up to, for example, the Aeromotive 525 LPH. Your requirement depends on power target, fuel type and system pressure, and flow typically drops as pressure rises.
• Fuel: If you plan to run ethanol blends, the pump must be designed for it. Check this for the specific part number.
• Fitment: DeatschWerks, for example, offers pumps with installation kits for the Mazda Miata and Cadillac CTS-V, while universal kits typically require modification in the pump housing.
• Electrical system: A more powerful pump typically draws more current, so wiring, fuse and relay must be able to keep up.

Installation and maintenance

Check whether the kit includes a new pre-filter, hoses and connectors, or whether you need to reuse original parts. With larger upgrades, the fuel filter, pressure regulator and injectors may also need to be assessed. Avoid frequently driving with an almost empty tank, as the pump is typically cooled by the fuel. Measure the fuel pressure after installation, and expect that a modified fuel supply may require adjustment of the engine management.

Frequently asked questions

How many LPH should my in-tank pump be able to deliver?

It depends on power target, fuel type and system pressure. Ethanol blends typically require more flow than petrol at the same power, and flow drops at higher pressure. So compare the manufacturer's flow data at the pressure your engine runs at.

Can I use a universal in-tank pump instead of a vehicle-specific kit?

Often yes, but universal kits typically require you to adapt the pump's position, hoses and connectors in the original pump housing. A kit for your specific car can make installation easier, if one is available for your model.

Why should the wiring be checked when upgrading the pump?

A more powerful pump typically draws more current. If the original wires are too thin, the voltage drop can cause lower flow and hot wires. A relay with a heavier power supply may therefore be necessary, depending on the pump and car.