The MGB fuel tank is mounted under the boot floor, with fuel drawn forwards to an electrical pump on the right-hand side of the car and then fed forward through a main copper pipe running along the underside of the chassis to the engine bay. The tank, filler arrangement, and pipework changed several times during production, and the correct components depend on the car’s chassis number and production period. Two principal fuel tank designs were used.
The original tank, fitted from 1962 to early 1965, was a wedge-shaped unit with a flat top and curved bottom, held in place by two mounting straps with rear hangers. From March 1965, a larger tank was introduced, approximately 12.7 gallons compared to the original 10 gallons, which was bolted directly to the boot floor rather than strap-mounted. This second design continued through chrome bumper production and into the rubber bumper era, though the drain plug was discontinued from January 1974.
From August 1976, both right-hand drive and North American cars received a redesigned tank with a combined fuel feed and gauge sender unit, and a shorter vertical filler neck in place of the earlier longer sloping type. A further revision to the filler tube and connection was introduced in late 1977. It is worth noting that, for 1975 to 1976 rubber bumper cars, the petrol tank may be replaced with the earlier bolt-on type together with the corresponding hose and filler pipe, an important consideration for owners of cars from this production window. The filler pipe and tank-to-filler hose differ between pre-1976 and post-1976 cars, as does the filler neck seal.
These components should be inspected whenever work is being carried out in this area, as the seals deteriorate with age and can allow fuel odour to escape into the boot. The tank sender unit also changed, earlier tanks used a separate sender unit sealed with a cork gasket, while the later redesigned tank incorporated a combined sender with a rubber seal and locking ring.
Tank-to-Pump Pipework
The tank-to-pump pipework varies across four main production periods: early chrome bumper cars up to 1964, later chrome bumper cars from 1964 to 1974, early rubber bumper cars from 1974 to September 1976, and late rubber bumper cars from September 1976 onwards. The differences reflect changes to the pump inlet connection type, with earlier cars using direct pipe connections and later cars using banjo unions with fibre washers. The main copper feed pipe running along the underside of the car from the boot to the engine bay is available separately and is secured by clips to the floor and bulkhead, the bulkhead clip differs between chrome bumper and rubber bumper applications.
In July 1975, all models changed from braided metal petrol hoses to polyurethane hoses in the rear fuel line area. Rubber fuel hose and steel pipe are both available by the metre for owners carrying out section repairs, and the associated clips for securing pipe to the boot floor and inner wings are available individually. The fuel tank fitting kit provides all the packing strips, bolts, nuts, washers, and caged nuts needed for a complete tank installation on bolt-on type tanks, and should be ordered alongside any replacement tank to ensure a secure and rattle-free fit. MGOC Spares carries replacement fuel tanks, sender units, filler pipes, filler neck seals, tank-to-filler hoses, foam seals, drain plugs, and all associated pipework and clips to cover the full MGB production run.