Aeromotive Fuel Pump: The Ultimate Guide to High-Performance Fuel Delivery
An Aeromotive fuel pump is a high-performance mechanical or electric component designed to deliver a consistent and adequate supply of fuel from the gas tank to the engine under all operating conditions. It is a critical upgrade for any vehicle where the factory fuel delivery system is insufficient, such as in modified street cars, race vehicles, trucks, and high-horsepower applications. Selecting the correct Aeromotive pump, installing it properly, and maintaining it are the most important factors for achieving reliable power and preventing engine damage. This guide provides a comprehensive overview of everything you need to know about Aeromotive fuel pumps, from basic principles to advanced installation techniques.
The primary function of any fuel pump, including those made by Aeromotive, is to provide a steady flow of fuel at the required pressure to the fuel injectors or carburetor. While a stock OEM fuel pump is designed to meet the needs of a factory engine, modifications that increase power—such as turbocharging, supercharging, engine displacement increases, or aggressive tuning—dramatically increase the engine's demand for fuel. An inadequate fuel supply leads to a lean air/fuel mixture, which causes power loss, overheating, detonation, and can result in catastrophic engine failure. Aeromotive Inc. specializes in engineering and manufacturing fuel system components that meet the extreme demands of high-performance environments, ensuring that the engine receives the volume of fuel it needs at a stable pressure.
Aeromotive offers a diverse product line to suit a wide array of applications. Understanding the different types of pumps and their intended use is the first step in selecting the right one.
In-Tank Fuel Pumps: These pumps are mounted inside the vehicle's fuel tank. This design is common in modern fuel-injected vehicles as it offers several benefits. Submerging the pump in fuel helps to keep it cool and lubricated, reducing the risk of cavitation and extending its life. Aeromotive in-tank pumps, such as those in the Stealth series, are often designed as direct replacements or retrofit solutions for factory units. They typically feature a bucket or housing that incorporates a filter sock and necessary fittings. These pumps are ideal for street-driven vehicles and moderate horsepower applications where maintaining a stock-like appearance and functionality is desired.
External Fuel Pumps: As the name implies, these pumps are mounted outside of the fuel tank, usually somewhere along the fuel line between the tank and the engine. External pumps, like the iconic Aeromotive A1000, are often capable of supporting very high flow rates and are commonly used in drag racing, road racing, and high-horsepower street builds. They require a separate pre-pump filter and must be mounted lower than the bottom of the fuel tank to allow fuel to gravity-feed to the pump inlet. External mounting can simplify service and replacement but requires careful planning of the fuel line routing and pump location.
Mechanical Fuel Pumps: These are engine-driven pumps, typically mounted on the engine's block or cylinder head and operated by an eccentric on the engine's camshaft. They are almost exclusively used with carbureted engines. Aeromotive mechanical pumps, like the Pro Series mechanical pump, are popular in classic muscle cars, hot rods, and nostalgia race classes where an original-style mechanical pump is required or preferred. Their output is directly proportional to engine RPM, and modern high-performance versions can support impressive power levels for a carbureted setup.
Electric Fuel Pumps: This is the most common type for modern fuel-injected vehicles and many high-performance applications. Electric pumps are powered by the vehicle's electrical system and can provide immediate fuel pressure as soon as the ignition is turned on (before cranking). They offer more consistent fuel pressure across a wider RPM range compared to mechanical pumps. All of Aeromotive's in-tank pumps and most of their external pumps are electric. They are available in various technologies, including brushless designs which offer extended life and consistent performance.
Choosing the correct Aeromotive fuel pump requires matching the pump's capabilities to the engine's demands. Several key factors must be considered.
Engine Horsepower: This is the starting point. Fuel pump requirements are directly related to the engine's brake-specific fuel consumption (BSFC) and target horsepower. BSFC is a measure of an engine's fuel efficiency. While a precise calculation is best, a general rule of thumb is that a naturally aspirated gasoline engine will require approximately 0.5 lbs of fuel per horsepower per hour. For a 500 horsepower engine, this equals 250 lbs/hr. Since fuel is measured in gallons, you convert this to gallons per hour (GPH). Dividing by 6 (since gasoline weighs approximately 6 lbs per gallon) gives a flow requirement of about 41.67 GPH. It is critical to select a pump that can meet this flow demand at your intended fuel pressure. Aeromotive provides flow charts for every pump, showing flow rate against pressure, allowing you to select a pump that exceeds your calculated needs.
Fuel Type: The type of fuel you plan to run significantly impacts pump selection. Standard gasoline has certain lubricity and cooling properties. Alcohol-based fuels like methanol (common in drag racing) or ethanol blends (like E85) require a much higher flow rate—often 30-40% more—because they contain less energy per gallon. Furthermore, some pump materials may not be compatible with aggressive alternative fuels. Aeromotive specifies which of their pumps are compatible with fuels like E85 and methanol. Using a pump not designed for these fuels can lead to premature failure.
Fuel System Type (Carbureted vs. Fuel Injected): This is a fundamental distinction. Carbureted systems operate at low pressure, typically between 4.5 and 7.5 PSI. They require a pump that can deliver high volume at low pressure. Fuel injection systems operate at much higher pressures, commonly between 40 and 60 PSI for port injection, and far higher for direct injection. A pump for a fuel-injected car must be capable of flowing the required volume while also maintaining this high system pressure. Using a carburetor pump on a fuel-injected engine will result in immediate and catastrophic failure, as it cannot achieve the necessary pressure.
Voltage: An electric fuel pump's performance is tied to the voltage it receives. While rated at 13.5 volts (standard automotive charging system voltage), actual voltage at the pump can be lower due to wiring losses. A pump's flow rate can drop significantly if it is not receiving adequate voltage. This is why proper wiring, using a relay and large-gauge wire, is non-negotiable for performance applications. Aeromotive's flow charts often show performance at multiple voltages to illustrate this point.
Installation and System Integration: Simply bolting on a high-flow pump is not enough. The entire fuel system must be upgraded to support it. This includes the fuel lines, filters, fittings, and regulator. Trying to push a large volume of fuel through a small factory fuel line or a clogged filter will create a restriction, causing a pressure drop and defeating the purpose of the high-performance pump. The fuel pump is just one component of a complete system, and all components must be matched for optimal performance.
Proper installation is paramount to the performance, reliability, and safety of an Aeromotive fuel pump. A poorly installed pump, even the best one available, will fail or perform poorly.
Safety First: Disconnecting Power: Always disconnect the negative battery cable before beginning any work on the fuel system. This prevents accidental sparks that could ignite fuel vapors.
Relieving Fuel System Pressure: For fuel-injected vehicles, the fuel system remains under high pressure even after the engine is off. This pressure must be safely relieved before disconnecting any fuel lines. Consult a service manual for the specific procedure for your vehicle, which often involves removing a fuel pump fuse and running the engine until it stalls.
Pump Location and Mounting:
- In-Tank Pumps: When installing an in-tank pump, ensure the replacement unit or retrofit assembly is securely mounted. The pump should be positioned to remain submerged in fuel as much as possible. Use the provided seals and lockrings correctly to prevent leaks. The fuel pickup sock should be clean and unobstructed.
- External Pumps: The mounting location for an external pump is critical. The pump must be located below the level of the fuel tank to allow fuel to gravity-feed to its inlet. Mount the pump securely using the provided hardware, isolating it from excessive vibration with rubber isolators if necessary. Protect the pump from road debris, heat, and moisture.
Wiring and Electrical Connections: This is a common area of failure. The fuel pump should always be wired through a relay that is triggered by a switched ignition source. The power for the pump itself should come directly from the battery through a fuse or circuit breaker of the appropriate amperage, placed close to the battery. Use automotive-grade wire of sufficient gauge to handle the pump's amperage draw over the required distance. All connections should be soldered and sealed with heat shrink tubing—never rely solely on crimp connectors. A poor electrical connection will cause voltage drop, reducing pump speed and flow, and generating heat that can damage the pump and create a fire hazard.
Plumbing and Fittings: Use fuel-rated hose and fittings for all connections. For high-pressure EFI applications, use hose specifically rated for EFI pressure; fuel injection hose has a much higher pressure rating than carburetor hose. Ensure all hose clamps and AN fittings are properly tightened. Use appropriate thread sealant or PTFE tape on NPT fittings to prevent leaks. Route fuel lines away from sharp edges, exhaust components, and moving parts.
Priming the System: After installation, reconnect the battery and turn the ignition key to the "on" position (without cranking the engine) for a few seconds. This allows the pump to prime the system and fill the lines and filter with fuel. Check all connections carefully for any signs of leakage. Only after verifying there are no leaks should you attempt to start the engine.
Even the highest quality fuel pump can experience issues. Understanding common problems aids in diagnosis.
Fuel Pump Failure (No Operation): If the pump does not run at all, the issue is often electrical. Check the fuse and circuit breaker first. Then, verify that power is reaching the pump using a multimeter. Check for a good ground connection at the pump. If power and ground are confirmed but the pump is silent, the pump motor has likely failed.
Low Fuel Pressure: This is a common symptom that can have many causes.
- Clogged Fuel Filter: A restricted filter is a primary cause of low flow and pressure.
- Voltage Drop: Insufficient voltage at the pump terminals will cause the pump to spin slower.
- Restricted Fuel Line: A kinked hose or a clogged line.
- Worn Pump: Internal wear can reduce a pump's output over time.
- Faulty Regulator: A stuck-open or defective fuel pressure regulator will not allow pressure to build.
High Fuel Pressure: This is almost always caused by a problem with the fuel pressure regulator. A stuck-closed regulator or a blocked return line will cause pressure to rise excessively.
Excessive Pump Noise: All electric fuel pumps generate some noise. However, a pronounced whining or screaming noise often indicates the pump is struggling. This can be caused by running the pump dry (without fuel), cavitation due to a restricted pre-pump filter, or air entering the inlet side of the pump. Continuous operation while noisy will lead to rapid failure.
Cavitation and Vapor Lock: Cavitation occurs when the pump tries to pull more fuel than is available at its inlet, creating vapor bubbles. These bubbles collapse inside the pump, causing noise and damaging internal components. Vapor lock happens when fuel in the lines vaporizes from engine heat, creating a vapor bubble that blocks flow. Both issues are addressed by ensuring the pump is fed properly, often with the help of a booster pump or a different feed strategy, and by keeping fuel cool.
Regular maintenance is key to long pump life and consistent performance.
Regular Filter Changes: The single most important maintenance task is regularly replacing the fuel filters. A clean pre-pump filter protects the pump from debris in the tank. A clean post-pump filter protects the injectors and engine. The service interval depends on the vehicle and fuel quality, but it should be done more frequently than a stock vehicle, especially if making high horsepower.
Using Quality Fuel: Contaminated or old fuel can cause premature wear. Avoid running the tank to empty, as this can cause the pump to pick up sediment from the bottom of the tank and run hot without adequate fuel for cooling.
Electrical System Checks: Periodically check the voltage at the pump terminals while the pump is running to ensure the wiring and relay are functioning correctly. Clean all electrical connections.
Aeromotive fuel pumps represent a critical investment in the performance and reliability of a high-output engine. They are not a generic commodity but rather precision-engineered components designed for specific, demanding roles. Success depends on a systems approach: carefully selecting the right pump for the application, integrating it into the fuel system with high-quality supporting components, executing a safe and correct installation with robust electrical wiring, and adhering to a disciplined maintenance schedule. When these principles are followed, an Aeromotive fuel pump will provide years of dependable service, delivering the lifeblood of fuel that a high-performance engine requires to make power safely and efficiently.