Visualize Your Build

Understanding the routing of your lines and the placement of your filters can be tricky. We’ve created The Ultimate Visual Guide to Your Car’s Fuel System & Tank Anatomy to help you map out your project with confidence.

Conclusion: Build It Right with EVIL ENERGY

Upgrading your gas fuel system is an investment in your vehicle’s heart. By answering 'how does a gas tank work?' and choosing components that handle modern fuel chemistry, you protect your engine and boost performance.

Ready to upgrade? From high-flow pumps to AN fittings and PTFE lines, find everything you need in the EVIL ENERGY Fuel System Collection.

The Ultimate Gas Fuel System FAQ: Performance, Mechanics, and Upgrades

Building a reliable high-performance vehicle starts with the heart of its delivery: the fuel system. Whether you are tackling a classic restoration or a modern engine swap, understanding the plumbing and physics of your gas fuel system is critical for both safety and power.

In this guide, we answer the most common questions enthusiasts ask when designing, maintaining, or upgrading their vehicle's fuel delivery components.

Q1: How does a gas fuel system work in a modern performance car?

A gas fuel system is a pressurized circuit designed to store, filter, and deliver fuel to the engine. It starts at the tank, where a pump sends fuel through high-pressure lines. A regulator maintains the exact PSI (Pounds per Square Inch) required, while filters remove contaminants that could clog injectors or carburetors. In performance builds, the fuel system must be capable of increasing flow instantly to match high-RPM air intake.

Q2: How does a fuel tank work to prevent engine sputtering?

If you’ve ever wondered how does a fuel tank works during hard cornering, the answer is internal baffling. Performance tanks feature vertical walls (baffles) that keep the fuel trapped around the pickup tube. Without these, fuel would slosh to one side, causing the pump to suck in air—a phenomenon known as fuel starvation that leads to engine hesitation or damage.

Q3: How do gas tanks work in terms of pressure and venting?

A gas fuel system cannot be a completely sealed box. As the fuel pump draws gas out, air must replace it to prevent a vacuum from collapsing the tank. Conversely, as fuel warms up, it expands and creates vapor. Modern tanks use specialized vent valves that allow the tank to 'breathe' while preventing raw fuel from leaking out during aggressive driving or a rollover.

Q4: What is the difference between a Return and a returnless fuel system?

• Return System: Uses two lines. One sends fuel to the engine, and the other returns unused fuel to the tank. This is the gold standard for performance because it keeps fuel moving and cooler.
• Returnless System: Uses a single line. The pump or an internal regulator manages the pressure. While simpler to plumb, it is more prone to 'heat soak' in extreme racing conditions.

Q5: Why is PTFE plumbing better for a high-performance fuel system?

Modern pump gas often contains ethanol (like E10 or E85), which is highly corrosive to traditional rubber hoses. Gas fuel system upgrades now almost exclusively use PTFE (PolyTetraFluoroEthylene) lines. PTFE is chemically inert, meaning it won’t break down, and it acts as a vapor barrier to prevent that 'gasoline smell' in your garage.

Q6: How does a fuel tank work when using an external fuel pump?

When using an external pump, the fuel system relies on gravity. Since most external pumps are excellent at 'pushing' but poor at 'pulling' fuel, they must be mounted lower than the fuel tank. The fuel flows out of a 'sump' at the bottom of the tank into the pump, ensuring a constant prime.

Q7: How do I know if my fuel system is failing?

Common symptoms of a failing gas fuel system include:

• Sputtering at high speeds: Indicates the pump cannot maintain flow.
• Hard starts: Suggests the system is losing 'prime' or pressure overnight.
• Loss of power: Often caused by a clogged fuel filter restricting the fuel system under load.

Q8: How does a fuel tank work in a 'Fuel Cell' configuration?

A fuel cell is a specialized version of a gas tank used in racing. It often contains an anti-slosh foam that divides the fuel into thousands of tiny pockets. This not only prevents fuel from shifting during high-G turns but also prevents a massive explosion in the event of a tank puncture.

Q9: Does the size of the fuel line matter for performance?

Absolutely. If your fuel lines are too small, they act as a bottleneck for your fuel system. Most 500-600 horsepower builds require at least a -6AN or -8AN line size to ensure the volume of gas can keep up with the engine's demand.

Q10: What is the most important maintenance task for a gas fuel system?

The most critical task is regular filter inspection. A high-performance fuel system usually has two filters: a coarse 'pre-filter' to protect the pump from large debris and a fine 'post-filter' (usually 10 microns) to protect the injectors. Replacing these annually ensures your pump doesn't have to work overtime to push fuel through a restriction.