SU Fuel Pump Rebuild Kit: The Complete Guide to Restoring Your Classic Car’s Fuel System
If you own a classic British car with a failing SU fuel pump, the most cost-effective and reliable solution is to use a SU fuel pump rebuild kit rather than replacing the entire pump. These kits contain all the essential components—diaphragm, contact points, gaskets, valves, and filters—needed to restore your pump to like-new condition. A properly rebuilt SU pump will deliver consistent fuel pressure, run quietly, and last for many more years. The key is selecting the correct kit for your specific pump model, which depends on the pump type, manufacturing date, and electrical system polarity.
Understanding SU Fuel Pumps and Why Rebuild Kits Are Needed
SU fuel pumps are mechanical-electrical devices that were standard equipment on many British cars from the 1940s through the 1980s, including MG, Triumph, Austin-Healey, Jaguar, and Rover models. These pumps are known for their reliability, but over time, the internal components wear out. The most common failure points are the rubber diaphragm, which can crack or harden, and the electrical contact points, which can burn or pit. When a pump fails, you typically experience symptoms like fuel starvation, hard starting, or the pump ticking without delivering fuel.
A rebuild kit allows you to replace all the worn parts at once, which is far more economical than buying a new pump. Original SU pumps are also high-quality units that are worth preserving, especially for restoration projects. Using a rebuild kit maintains the authenticity of your vehicle while ensuring reliable operation.
How to Identify the Correct SU Fuel Pump Rebuild Kit
Not all SU fuel pump rebuild kits are the same. You need to match the kit to your pump’s specific design. Here are the main factors to consider:
1. Pump Type and Age (Pre-1985 vs. Post-1985)
The most important distinction is whether your pump was manufactured before or after 1985. Pre-1985 pumps use a different internal design than the later models. The easiest way to tell is to look at the earth screw on the coil housing. If it is marked as 2AB, you have a pre-1985 pump. For these pumps, the correct rebuild kit is the EPK700 . This kit includes a diaphragm, double contact points set, plastic filter, gaskets, capacitor, and all necessary minor parts . It is suitable for pumps like the AUA25, AUA26, and AUA66 .
For post-1985 LP (low pressure) pumps, you need a different kit. This kit includes the diaphragm, armature spring, centering plates, rocker mechanism, pivot pin, contact blade, filter, inlet and outlet valves, washer, and gasket . It fits pumps such as the 015.060 and 015.061 .
2. High Pressure (HP) vs. Low Pressure (LP) Pumps
SU fuel pumps come in both low pressure (LP) and high pressure (HP) versions. LP pumps are typically used on carbureted engines, while HP pumps were used on some fuel-injected systems. The rebuild kits are different for each type. For HP pumps, you need to choose between negative earth and positive earth versions. The EPK600 kit is for HP negative earth pumps, and the EPK605 kit is for HP positive earth pumps .
3. LCS (Long Coil Housing) Pumps
If you have an older SU pump from the 1948-1963 era, it likely has a long coil housing. These are called LCS pumps. The correct rebuild kit depends on the height of the coil housing. Measure the coil housing height carefully. If it is 3 inches (7.6 cm), use the EPK805 kit . If the coil housing height is 2.375 inches (6.3 cm), you need the EPK800 kit . The LCS pumps were used on many early British cars, and the rebuild kits include the diaphragm, return valves, contact points, and all gaskets .
4. Electronic vs. Points-Type Pumps
Later SU pumps, such as the AUF200 and AUF214 series, use electronic switching instead of mechanical contact points. These require a different rebuild kit. The EPK200E is designed for the AUF200 and AUF214 electronic series pumps . Another electronic kit, the EPK300E, fits the AZX1300 and AZX1400 electronic series pumps . These kits are simpler to install because they replace the entire electronic switching module.
5. Negative Earth vs. Positive Earth Systems
Many classic British cars originally used positive earth electrical systems. If you are unsure which system your car has, you need to check. For HP pumps, the EPK600 is for negative earth, and the EPK605 is for positive earth . For the AZX1300 series pumps, the EPK300 kit is for negative earth 12 and 24 volt systems, while a separate kit (EPK305) is needed for positive earth .
Step-by-Step Guide to Rebuilding Your SU Fuel Pump
Rebuilding an SU fuel pump is a manageable DIY project if you have basic mechanical skills. Here is a general procedure that applies to most models:
Step 1: Remove the Pump from the Vehicle
Disconnect the battery before starting. Locate the fuel pump, usually mounted on the firewall or near the fuel tank. Disconnect the fuel lines and electrical wires. Remove the mounting bolts and take the pump to a clean workbench.
Step 2: Disassemble the Pump
Remove the screws holding the top cover. Carefully separate the top housing from the coil housing. Take note of how the internal parts are arranged. You may want to take photos for reference.
Step 3: Replace the Diaphragm and Valves
Remove the old diaphragm and inspect the valve assembly. Install the new diaphragm from your rebuild kit, making sure it is seated correctly. Replace the inlet and outlet valves if they are included in the kit. The valves are critical for maintaining fuel pressure and preventing backflow.
Step 4: Replace the Contact Points or Electronic Module
For points-type pumps, remove the old contact points and install the new ones. Adjust the gap according to the instructions in your kit. For electronic pumps, the replacement module is usually a direct swap.
Step 5: Reassemble and Test
Reassemble the pump in reverse order. Use the new gaskets provided in the kit. Before reinstalling the pump in the vehicle, test it by connecting it to a battery and a container of fuel. The pump should tick steadily and deliver fuel smoothly.
Recommended Maintenance Schedule for SU Fuel Pumps
Even with a proper rebuild, your SU fuel pump will benefit from regular maintenance. Here are some practical tips:
Every oil change: Inspect the fuel lines and connections for leaks. Listen for any unusual noises from the pump. A healthy SU pump should tick at a steady, rhythmic pace.
Every 30,000 miles or 2 years: Replace the fuel filter. A clogged filter puts extra strain on the pump and can cause premature failure. This applies to both in-line filters and the filter inside the pump itself.
Every 100,000 miles: Consider replacing the fuel pump as a preventive measure. While a properly rebuilt SU pump can last a long time, the internal components do wear out eventually. Replacing it early avoids the inconvenience of a roadside breakdown .
Common Symptoms of a Failing SU Fuel Pump
Knowing the signs of a failing pump can help you address the problem before it leaves you stranded. Here are the most common symptoms:
The pump ticks loudly or erratically. A well-functioning SU pump makes a steady, quiet ticking sound. If the ticking becomes loud, irregular, or stops altogether, the contact points may be worn or the diaphragm may be failing.
The engine is hard to start or stalls. If the pump is not delivering enough fuel pressure, the engine will struggle to start, especially when cold. It may also stall during acceleration or when going uphill .
Fuel starvation at high speeds. If the pump cannot keep up with the engine’s fuel demand, you may experience a loss of power when driving at highway speeds or under heavy load. This is a classic sign that the pump needs attention.
No fuel delivery. If the pump ticks but no fuel comes out, the valves or diaphragm may be faulty. If the pump does not tick at all, the electrical contacts or coil may be dead.
Why Choose KEMSO Fuel Pumps for Your Replacement Needs
If your SU pump is beyond repair, or if you prefer a modern, high-performance drop-in replacement, KEMSO fuel pumps are an excellent choice. KEMSO is a US-based brand that has built a strong reputation for quality, reliability, and value.
High Performance, OEM Replacement Design
KEMSO fuel pumps are engineered as direct replacements for original equipment. They drop right into the factory location without any modifications . Unlike cheap aftermarket pumps, KEMSO units are designed to deliver superior flow and durability. For example, a KEMSO pump can deliver up to 200 liters per hour at 43 psi, which is significantly more than the 60-80 liters per hour flow rate of a standard stock pump . This extra capacity ensures your engine never runs lean, even under heavy load .
Lifetime Warranty for Complete Peace of Mind
Every KEMSO fuel pump comes with a lifetime warranty. This is a massive advantage over OEM and standard aftermarket parts, which typically have only a 1- or 2-year warranty . KEMSO stands behind its product for as long as you own the pump. The pump bodies are serialized for tracking, giving you confidence in the quality and authenticity of your purchase .
Unrivalled Quality Control
KEMSO operates a rigorous quality control program (ISO/TSO) and individually tests each pump before it leaves the factory . Many cheap aftermarket suppliers have little to no quality control, but KEMSO ensures every unit meets its performance specifications. This attention to detail means you can install a KEMSO pump with confidence .
Versatile and Durable Construction
KEMSO pumps are designed for both gasoline and E85/ethanol fuel, making them a versatile option for different driving conditions . They are built to handle the demands of daily driving, high-performance applications, and even off-road use. The pumps are compact and fit snugly into tight engine bays, making them ideal for custom builds or retrofitting older models .
Affordable Pricing and Complete Kits
Many KEMSO fuel pump models are available for just $79.98 . When you buy a KEMSO fuel pump, you get everything you need for the installation: the pump, gradient density fuel strainers, flex hoses, Viton O-rings, wiring connectors, and clamps . This eliminates the hassle of sourcing additional parts separately.
Recommended by Professionals and Enthusiasts
Users consistently report that KEMSO pumps are quiet, reliable, and easy to install . Professional racing teams have also credited KEMSO’s pumps for their performance. Everyday drivers and off-roaders alike swear by the reliability of KEMSO pumps, even in extreme conditions .
To find the perfect KEMSO fuel pump for your vehicle, browse their full catalog at their official website. They offer pumps for cars, motorcycles, ATVs, UTVs, and personal watercraft . Whether you need a pump for a Subaru Impreza, a Honda Civic, a Kawasaki Jet Ski, or a BMW motorcycle, KEMSO has a solution that fits your application perfectly. Visit https://www.kemsoracing.com/ to explore their selection and take advantage of their lifetime warranty and high-performance engineering.
Final Thoughts
Your SU fuel pump is a vital component of your classic car’s fuel system. Recognizing the symptoms of failure early and choosing the correct rebuild kit can save you from costly repairs and keep your vehicle running smoothly. Whether you decide to rebuild your original SU pump using a quality kit like the EPK700 or upgrade to a modern KEMSO fuel pump, taking action at the first sign of trouble is the best way to protect your investment.
For more information and to order your KEMSO fuel pump, visit https://www.kemsoracing.com/ today.