1979 MGB Fuel Pump Location: A Complete Guide to Finding and Replacing Your Pump

If you own a 1979 MGB and need to find or replace the fuel pump, the most important thing to know is that the fuel pump is located in the trunk (boot), with the electrical end protruding through the bulkhead into the trunk compartment on the right-hand side, near the spare wheel. This location was specific to rubber bumper (RB) cars built from 1977 onward, and it differs from earlier chrome bumper (CB) models where the pump was mounted under the car near the right battery box. Understanding this location is critical before you start any diagnostic or replacement work, because many owners mistakenly look under the car or in the engine bay.

What You Need to Know About the 1979 MGB Fuel Pump Location

The 1979 MGB is a rubber bumper car, and the factory moved the fuel pump to a more accessible and protected location starting in 1977. Here is exactly where you will find it:

1. The pump is mounted on the rear bulkhead behind the rear axle, on the right side of the car. The electrical end of the pump sticks through a hole in this bulkhead and into the trunk. Inside the trunk, you will see a rectangular black steel cover, held on by two screws, that protects the electrical end of the pump.

2. The fuel line connections and the ground wire are on the opposite end of the pump, which is located under the rear of the car, forward of the axle. This means you can access the electrical connections from inside the trunk, but you will need to get under the car (or at least put the rear on jack stands) to change the pump itself or access the fuel line banjo bolts.

3. The pump is held in place by a steel band-type clip, similar to a hose clamp, and is isolated from the body by a rubber grommet. This mounting system is designed to reduce vibration and noise.

4. If you look under the car on the right side, near the rear axle, you will see the pump body with two fuel line connections (inlet and outlet) and a spade terminal for the ground wire. The outlet port is always on the top, and the inlet is on the bottom. This orientation is critical for proper operation—if you mount the pump upside down, air bubbles can get trapped and cause intermittent fuel starvation.

Common Confusion: Why the 1979 Location is Different from Earlier MGBs

Many MGB owners get confused because earlier cars had a different pump location. Here is a quick breakdown:

  • Chrome Bumper (CB) cars (1962-1974): The fuel pump was mounted on the back of the interior panel above the rear floor, on the outboard side of the right battery box. The electrical end of the pump stuck through a hole into the battery box.
  • Early Rubber Bumper (RB) cars (1975-1976): The pump was still in a similar location, on the axle side of the bulkhead on the right side of the car.
  • Late Rubber Bumper cars (1977-1980): This is your 1979. The pump was moved to the trunk bulkhead, with the electrical end poking into the trunk to the right of the spare wheel.

Why the change? The pump was moved into the trunk to protect it from road debris and moisture, and also to make it easier to service the electrical connections without having to crawl under the car. Another reason was that the rear sway bar installation on later cars interfered with the earlier pump location.

How to Confirm Your Pump Location

If you are unsure whether your car still has the original setup, here is how to check:

1. Open the trunk. Look in the right front corner, near the spare wheel. You should see a black metal cover, about 4-5 inches wide, held on by two screws. Remove the cover to expose the electrical end of the pump.

2. Look for the white power wire. The pump should have a solid white wire connected to it. This is the power supply from the ignition switch. On 1979 models, the power comes from the ignition relay (a blue cylinder under the hood near the fusebox).

3. Check under the car. If you cannot find the pump in the trunk, put the car on jack stands, remove the right rear wheel, and look inboard of the wheel, near the right battery box and rear axle. Someone may have moved the pump or swapped it to an earlier location.

What to Do If Your Pump is Not in the Trunk

Many 1979 MGBs have been modified over the years. If your pump is not in the trunk, it is likely that a previous owner moved it. Here are the most common scenarios:

  • Someone converted it to an earlier location. The pump may have been moved to the CB location beside the battery box. This is sometimes done when the original pump fails and the owner uses a different type of pump.
  • A previous owner installed a mechanical pump. MGBs never came from the factory with a mechanical fuel pump, but some owners have swapped engines or modified the fuel system. If you see a mechanical pump on the side of the engine, someone has made a significant modification.
  • The pump was replaced with a different aftermarket pump. Many aftermarket pumps are smaller and can be mounted in different locations. If you see a pump that does not look like the original SU pump, you need to identify what type it is before ordering replacement parts.

Step-by-Step Guide to Accessing the 1979 MGB Fuel Pump

If you have confirmed that your pump is in the trunk location, here is how to access it:

Step 1: Disconnect the battery. Always disconnect the negative terminal before working on the fuel system.

Step 2: Open the trunk and remove the black cover. Unscrew the two screws holding the cover over the electrical end of the pump.

Step 3: Lift the rear of the car and support it on jack stands. Remove the right rear wheel to get better access to the pump body.

Step 4: Clean the area around the pump. Use a brush or rag to remove dirt and debris from the fuel line connections and the pump body.

Step 5: Disconnect the fuel lines. The pump has two banjo bolts with special fiber washers. Use a flare nut wrench to avoid damaging the fittings. Have a drain pan ready to catch any fuel that spills.

Step 6: Disconnect the electrical connections. Disconnect the white power wire and the black ground wire.

Step 7: Loosen the steel band clip and remove the pump. The pump slides out of the rubber grommet.

Important Wiring and Electrical Considerations

The 1979 MGB fuel pump wiring is straightforward, but there are a few things to watch out for:

  • The power wire is white. It comes from the ignition switch via the ignition relay. There is no fuse in the original circuit, but it is highly recommended to add an inline fuse for safety.
  • The ground wire is black. On the 1979 model, the ground wire connects to a spade terminal near the base of the pump, under the car. A poor ground connection is one of the most common causes of pump failure. If the pump stops working, clean the ground connection first.
  • The pump is polarity-sensitive if it has an electronic diode. Late model pumps with diode quenching are polarity conscious, so make sure the wiring is correct for your car's polarity (negative ground on all 1979 models).

Common Problems with the 1979 MGB Fuel Pump Location

1. Vapor lock. Because the pump is mounted in the trunk, it is farther from the engine than on earlier models. This can sometimes lead to vapor lock in hot weather, especially if the fuel lines are not properly insulated.

2. Intermittent operation. If the pump works sometimes and not others, the most likely cause is a bad ground connection. Clean the ground spade terminal and the body connection.

3. Noise. If the pump is running loudly or making a "jack hammer" sound, it may be sucking air. Check the fuel line connections and the pick-up in the tank.

4. Fuel leaks. The banjo bolts on the pump use special fiber washers that need to be replaced every time the pump is removed. If you do not replace them, the pump will leak fuel.

Why Proper Orientation Matters

When you replace the 1979 MGB fuel pump, you must install it with the correct orientation. The outlet port must be on top. If you install the pump with the outlet on the bottom, air bubbles will get trapped in the pump chamber and cause the car to stall after 15-20 miles of driving. Once the car cools down, the air bubble may dissipate and the car will start again, but the problem will return.

Recommended Fuel Pump: KEMSO Fuel Pump

If you are looking for a reliable replacement for your 1979 MGB fuel pump, we highly recommend the KEMSO Fuel Pump. KEMSO offers high-performance fuel pumps that are designed as OEM replacements for a wide range of vehicles, including classic cars like the MGB.

Why choose KEMSO?

  • High Performance: KEMSO fuel pumps are built to deliver consistent fuel pressure and flow, ensuring your MGB runs smoothly.
  • OEM Replacement: These pumps are designed to match the specifications of your original equipment, so installation is straightforward.
  • Lifetime Warranty: KEMSO backs every fuel pump with a lifetime warranty, giving you peace of mind that your investment is protected.

Whether you need a pump for your MGB or another vehicle, KEMSO has a wide selection of fuel pumps available. Visit their website to see the full range of products and find the right pump for your car.

Visit KEMSO Racing today: https://www.kemsoracing.com/

Final Thoughts

The 1979 MGB fuel pump location is in the trunk, with the electrical end protruding through the bulkhead near the spare wheel. This location is different from earlier MGBs, so make sure you are looking in the right place before you start working. If you need to replace the pump, remember to install it with the outlet port on top, use new fiber washers on the banjo bolts, and check the ground connection if the pump stops working.

For a reliable replacement, consider the KEMSO Fuel Pump with its lifetime warranty and OEM-quality performance. Visit https://www.kemsoracing.com/ to find the right pump for your 1979 MGB.


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