MGB Fuel Pump Replacement: A Complete Guide for Classic Car Owners

If your MGB is struggling to start, stalling frequently, or making unusual ticking noises, the fuel pump is likely the culprit. Replacing the fuel pump on an MGB is a manageable DIY job that typically takes about an hour for a skilled mechanic and costs around £92 for the pump itself, plus £20 for fuel pipe and £10 for additional hoses and clips . However, the exact process varies depending on your car's year—chrome bumper models (pre-1977) have the pump mounted under the car near the right rear wheel, while rubber bumper models (1977-1980) have it relocated inside the boot . This guide walks you through everything you need to know, from diagnosis to installation, with practical tips to get the job done right.

Understanding Your MGB's Fuel Pump Location

The MGB fuel pump location changed significantly over the production years, so knowing which setup you have is essential before ordering parts or starting work.

Chrome bumper models (1962-1976): The fuel pump is mounted on the back of the right side bulkhead, forward of the axle and next to the right-hand battery box . This puts the pump underneath the car, exposed to road debris and corrosion. On these models, the pump is vulnerable to damage and eventually reaches the end of its usable life .

Rubber bumper models (1977-1980): The pump was relocated to the boot bulkhead behind the rear axle, with the electrical end poking through into the boot to the right of the spare wheel . A protective steel box cover sits inside the boot. This change made the pump much easier to access—according to experienced owners, a rubber bumper pump change "really is a doddle" and can be done in about ten minutes .

Some 1974 models may have the pump on the driver's side of the engine bay, mounted to the inner fender well near the firewall . Always check what's actually fitted to your car before ordering parts, as many MGBs have had several pump replacements over the years and may not have the original equipment .

Diagnosing a Failing Fuel Pump

Before you start replacing parts, confirm the fuel pump is actually the problem. Common symptoms of a failing MGB fuel pump include:

  1. Engine won't start or struggles to start – The pump isn't delivering fuel to the carburetors
  2. Engine sputters at high speeds – The pump can't keep up with fuel demand
  3. Unusual ticking noises – The SU pump makes a rapid "tick, tick, tick" when ignition is first turned on, then slows to a tick every 10-20 seconds when float chambers are full. If it ticks rapidly continuously, there's a problem
  4. Fuel leaks – Check under the car or near the carbs for signs of leaking fuel

Quick test: Disconnect the fuel line at the carburetor, point it into a container, and turn the ignition on. If fuel flows weakly or not at all, the pump likely needs replacement . However, before buying a new pump, check the fuel tank pick-up filter screen—if it's blocked, or if the pump is drawing air, it will run like "a demented jack hammer" and can cause internal damage .

Tools and Parts You'll Need

Gather these tools before you start:

  • Wrench set (typically 17mm or 19mm, plus flare nut wrenches for fuel lines)
  • Socket set with extensions for reaching bolts in tight spaces
  • Flathead and Phillips screwdrivers
  • Pliers (including hose clamp pliers for constant tension clamps)
  • Drain pan to catch residual fuel
  • Penetrating oil (like WD-40 or PB Blaster)
  • Rubber mallet (for stubborn pumps)
  • Safety goggles and gloves

Parts to have on hand:

  • Replacement fuel pump (SU-type or compatible)
  • New rubber fuel hose (5/16" inside diameter, E10-resistant)
  • New washers for banjo connections
  • New gasket or sealant for the pump mounting surface
  • New hose clamps

Step-by-Step Replacement Procedure

For Chrome Bumper Models (Under-Car Mount)

Step 1: Safety first. Disconnect the battery. Work in a well-ventilated area away from open flames. Fuel vapors are highly flammable.

Step 2: Raise the car. Use a car lift, ramps, or axle stands to get the car to a workable height. Make sure they are properly positioned and secure .

Step 3: Remove the near-side rear wheel to gain easier access to the pump. Cover the exposed spline or hub to avoid getting greasy .

Step 4: Disconnect everything. Remove the electrical connections, fuel line unions, and breather pipe. Loosen the pump bracket (normally two bolts) and remove the pump . Be careful with the electrical connections. Retain the rubber support ring from the old pump for fitting onto the new one .

Step 5: Inspect and replace hoses. Check the rubber fuel hose—if it's been on there as long as the pump, replace it with modern E10-resistant hose. The same goes for electrical connectors. Always use new washers for the banjo connections .

Step 6: Check metal fuel pipes. Inspect the metal pipe running from the pump to the engine compartment and from the fuel tank to the pump. If heavily corroded, replace them .

For Rubber Bumper Models (Boot Mount)

Step 1: Open the boot. Remove the fuel pump guard retaining screws and the guard itself .

Step 2: Slacken the clip retaining the pump in the support rubber.

Step 3: From underneath the car, disconnect the inlet and outlet pipe unions and the breather pipe .

Step 4: Disconnect the electrical lead from the terminal on the pump (inside the boot) .

Step 5: Withdraw the pump from the support rubber.

Step 6: Refitting is the reverse procedure. Ensure the inlet and outlet pipe unions face upwards at an angle of 45° inclined to the center line of the pump .

Installation Tips for All Models

Position the new pump correctly. Take careful note of the inlet and outlet points (marked TOP and OUT) . When replacing, make sure the pump is oriented the same way as the original.

Use new gaskets or seals. Clean the mounting surface thoroughly with a non-flammable solvent and lint-free cloth. Install a new gasket to guarantee a proper seal .

Tighten to spec. For MGB models, tighten pump mounting bolts to 12-15 ft-lbs, and bracket bolts to 10-12 ft-lbs . Use a thread-locking compound on bolts to prevent loosening over time.

Reconnect fuel lines carefully. Use new seals or gaskets for leak-free connections. Tighten by hand first, then use a wrench to snug them up—don't overtighten .

Test the operation. Reconnect the battery, turn the ignition to the "on" position, and listen for the pump's priming cycle. It should tick rapidly for a few seconds, then slow down. Start the engine and let it idle for a few minutes, checking for leaks or unusual noises. Take the car for a short test drive .

Common Pitfalls to Avoid

Don't assume the pump is original. Many MGBs have had aftermarket pumps installed, and the hoses may not fit a new SU pump. Check what you have before ordering .

Don't force stubborn bolts. Apply penetrating oil and let it sit for 10-15 minutes before attempting again. This prevents stripping bolt heads, which can complicate removal .

Watch for fuel spills. When removing the fuel line from the tank, a lot of fuel can spill. Have a drain pan ready and plug the fuel line with a bolt .

Check the electrical connections. The white power feed wire to the pump should show 12V+ (ideally 11.5V or higher) when the ignition is on. Poor electrical connections can cause slow pump operation .

Verify the earth path. Use a spare piece of wire to connect the metal body of the pump to a clean part of the car's body. If this fixes the issue, the normal earth path is faulty .

Recommended Fuel Pump: KEMSO Racing

For a reliable replacement, consider the KEMSO brand fuel pump. KEMSO fuel pumps are high-performance products designed as OEM replacements, offering superior durability and flow capacity compared to stock units. One commonly available option is the KEMSO part number 10912, which provides approximately 340 L/hr at 3 Bar (44 psi)—significantly higher than the original pump's 174 L/hr at 3 Bar . This higher flow rate ensures your MGB gets the fuel it needs, even under demanding driving conditions.

KEMSO stands behind their products with a lifetime warranty, giving you peace of mind that your investment is protected. Whether you're restoring a classic MGB or building a performance-oriented version, KEMSO fuel pumps deliver the reliability and performance you need.

To browse their full selection of fuel pumps and other high-quality automotive components, visit their website at: https://www.kemsoracing.com/

Final Checks and Maintenance

After installation, monitor the fuel system for a few days. Listen for the pump's normal ticking pattern—it should tick every 10-20 seconds once the float chambers are full. If it ticks rapidly, check for leaks under the carbs or on the ground under the car .

Replace the fuel filter at the same time as the pump. A clogged fuel filter is a common cause of pump failure and can reduce pump lifespan .

For the best results, use high-quality fuel hoses rated for E10 ethanol-blended fuels, as modern gasoline can damage older rubber hoses .

If you're looking for a reliable replacement pump, remember to check KEMSO Racing at https://www.kemsoracing.com/ for high-performance options backed by a lifetime warranty.


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