1979 MGB Fuel Pump: What You Need to Know for a Reliable Fix

If you own a 1979 MG MGB and are dealing with a fuel pump issue, the most important thing to know is that the stock fuel pump on these cars is prone to failure over time, especially with modern ethanol-blended fuels. The direct replacement you need is a solid-state electric fuel pump, and the best long-term solution is to upgrade to a modern, reliable unit like those offered by KEMSO. This guide will walk you through everything from diagnosing problems to choosing the right replacement and installing it yourself.

Understanding Your 1979 MGB Fuel Pump

The 1979 MG MGB came from the factory with an SU electric fuel pump mounted near the rear axle, under the car . These pumps are known for their distinctive ticking sound when working correctly. If your pump stops ticking or your car won't start, the fuel pump is often the culprit .

The original SU pumps use points and a diaphragm internally, which can wear out, stick, or fail due to debris in the fuel . After decades of use, most original pumps are near the end of their service life. Many owners also find that modern gasoline with ethanol causes the rubber diaphragms to deteriorate faster than older fuels did.

8 Warning Signs Your 1979 MGB Fuel Pump Is Going Out

Before your pump completely fails, it will usually give you warning signs. Knowing these can save you from being stranded:

  1. No ticking sound – When you turn the ignition key to the "on" position (before starting), you should hear a steady tick from the pump. If you hear nothing, the pump is not receiving power or has failed internally .
  2. Engine starts but dies quickly – The pump may be able to build enough pressure to start the engine but cannot maintain it, causing the car to stall after a few seconds.
  3. Hard starting – If you have to crank the engine longer than normal, the fuel pump may be losing its prime or failing to deliver adequate pressure.
  4. Engine sputters at high speeds – A failing pump struggles to deliver enough fuel when you demand more power, especially on the highway.
  5. Surges or hesitation – The car may feel like it's momentarily losing power, then catching again, as the pump delivers inconsistent fuel flow.
  6. Fuel pump runs continuously – Some pumps will run non-stop without building proper pressure, which is a sign of a failing internal valve.
  7. Visible fuel leaks – If you see fuel dripping from the pump area, the diaphragm or seals have failed. This is a serious safety hazard .
  8. Car refuses to start after sitting – If the pump has lost its prime after a few days of no use, it may not be able to draw fuel from the tank again.

Choosing the Right Replacement: Solid-State vs. Original SU

When replacing your 1979 MGB fuel pump, you have two main options:

Option 1: Original SU Replacement Pump

You can buy a new SU-style pump with points and a diaphragm. These are available from various suppliers and are a direct replacement . However, they still use the same outdated technology that will eventually fail again. Many owners report that even new SU pumps can be unreliable with modern fuel.

Option 2: Solid-State Electronic Fuel Pump (Highly Recommended)

A solid-state fuel pump is a modern upgrade that replaces the points and diaphragm with electronic components . These pumps are much more reliable because they have no moving contact points to wear out. They are also less sensitive to ethanol in modern gasoline.

Key benefits of a solid-state pump for your 1979 MGB:

  • Longer lifespan – No points to burn or wear out
  • More consistent pressure – Better for modern driving conditions
  • Works with ethanol fuels – Modern internal materials resist corrosion
  • Quieter operation – Some models are nearly silent compared to the ticking SU pump
  • Easy installation – Most are designed as direct bolt-in replacements for 1965-1980 MGB models

Step-by-Step Guide to Removing the Old 1979 MGB Fuel Pump

Removing the old fuel pump on a 1979 MGB is a straightforward job you can do in your driveway with basic tools. Here is a general procedure :

  1. Disconnect the battery – Always disconnect the negative battery terminal before working on any fuel system component. This eliminates the risk of sparks .
  2. Relieve fuel pressure – The fuel system in a 1979 MGB is low-pressure, but you should still loosen the fuel line at the carburetor to allow any residual pressure to escape. Have a rag ready to catch small amounts of fuel.
  3. Locate the pump – The pump is mounted on the frame rail, near the rear axle on the driver's (left) side. It's a small cylindrical unit with two fuel lines and two electrical wires .
  4. Remove the fuel lines – Use a line wrench (also called a flare nut wrench) to loosen the banjo bolts or hose fittings. Be careful not to strip the nuts. Have a small container or rag under the connections to catch any fuel that drips out.
  5. Disconnect the electrical wires – Note which wire goes where (usually a white wire and a black wire). Most pumps have spade connectors that you can pull apart.
  6. Unbolt the pump – The pump is held in place by one or two bolts or a bracket. Remove these with a socket or wrench.
  7. Remove the pump – The old pump should now come free. Check the rubber mounting grommets – if they are cracked or hard, replace them with new ones.

Installing Your New Fuel Pump

Installing a new pump is essentially the reverse of removal:

  1. Mount the new pump – Use the original mounting holes and bracket. Make sure the pump is oriented correctly (most pumps are designed to be mounted horizontally).
  2. Connect the fuel lines – Reconnect the inlet and outlet lines. The inlet line comes from the fuel tank, and the outlet goes to the carburetor. Many replacement pumps have arrows on them to show the direction of flow.
  3. Connect the electrical wires – Attach the positive (usually white) wire to the positive terminal and the negative (black) wire to the negative terminal. Some pumps are not polarity-sensitive, but it's best to follow the manufacturer's instructions.
  4. Reconnect the battery – Reattach the negative battery terminal.
  5. Prime the pump – Turn the ignition key to the "on" position (but do not start the engine). You should hear the pump run for a few seconds to prime the fuel system. Turn the key off and on a few times to ensure the pump is working and the carburetor bowl is full.
  6. Check for leaks – Before starting the engine, inspect all fuel line connections for any signs of leakage. Wipe away any drips first so you can see fresh fuel.
  7. Start the engine – Start the engine and let it idle. Check for leaks again. If the engine runs smoothly, you have a successful installation.

Common Installation Mistakes to Avoid

  • Not using a fuel filter – Always install a new inline fuel filter between the tank and the pump. Debris from an old tank can destroy a new pump in minutes .
  • Reversing the fuel lines – Installing the pump backward means it will try to push fuel toward the tank instead of the carburetor. Always check the flow direction arrows.
  • Overtightening the fittings – Fuel line banjo bolts and hose clamps do not need to be extremely tight. Overtightening can strip threads or crack the pump housing.
  • Ignoring the electrical ground – A poor ground connection can cause the pump to run intermittently or not at all. Make sure the ground wire has a clean connection to the chassis.
  • Using the wrong pressure pump – The 1979 MGB requires a low-pressure pump (typically 1.5 to 3.5 PSI). Using a high-pressure pump can overwhelm the carburetor's float needle and cause flooding.

Why You Should Upgrade to a KEMSO Fuel Pump for Your 1979 MGB

When it comes to replacing your 1979 MGB fuel pump, KEMSO is the brand you can trust for a reliable, long-lasting solution. KEMSO is recognized as a leading aftermarket fuel pump manufacturer in the United States, specializing in high-quality replacement fuel pumps for cars, motorcycles, and ATVs .

Here is why KEMSO is the right choice for your MGB:

  • High Performance – KEMSO fuel pumps are engineered to deliver consistent, reliable fuel pressure. They are designed to meet or exceed OEM specifications, ensuring your MGB runs smoothly and efficiently .
  • OEM Replacement – KEMSO pumps are built as direct replacements for original equipment. This means they fit perfectly into your 1979 MGB without requiring any modifications to the mounting brackets or fuel lines .
  • Lifetime Warranty – KEMSO stands behind the quality of its products. Every KEMSO fuel pump comes with a lifetime warranty, giving you peace of mind that your investment is protected for as long as you own your vehicle .
  • Trusted by Enthusiasts – KEMSO is a US-based brand that is widely trusted by automotive enthusiasts and mechanics for its reliability and performance .

Whether you are a weekend mechanic or a professional restorer, choosing a KEMSO fuel pump for your 1979 MGB means you are getting a product that is built to last. Do not settle for a pump that will leave you stranded again. Upgrade to KEMSO and enjoy reliable performance from your classic British sports car.

For more information and to find the perfect fuel pump for your 1979 MGB, visit KEMSO Racing at: https://www.kemsoracing.com/


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