The MGF and MG TF fuel tank is located behind the seats, within the central packaging area ahead of the engine. This is a mid-engine layout choice: the tank mass sits close to the car's wheelbase centre alongside the engine, contributing to the centralised mass distribution that gives the MGF and TF their well-regarded handling. Access for tank or fuel pump service is from within the cabin, the soft-top rear stowage liner is lifted to reveal an access panel in the engine compartment bulkhead, and the pump/sender flange is reached through this panel. The access arrangement is unusual to anyone familiar with front-engined cars where the tank is typically under the rear boot floor, but it is purpose-designed for the mid-engine layout.
Tank capacity is 50 litres (11 gallons), with several more litres of reserve capacity below the gauge's "empty" mark, experienced owners report putting 52 or even 55 litres in a drained tank, although this is not a practice to rely on.
The MY2000 Double-Skinned Tank
A significant production change occurred at the Mk2 / Model Year 2000 facelift, launched in autumn 1999, when a double-skinned fuel tank replaced the original single-skin tank. This change is confirmed in MG Rover factory technical references and widely documented by the MGF Register and MG Car Club. The double-skin construction provides an additional layer of vapour and liquid containment, and was introduced specifically to resolve the fuel vapour smell that affected a proportion of earlier Mk1 MGFs, a characteristic complaint of the pre-MY2000 cars where fuel odour would occasionally enter the cabin, particularly when parked in warm conditions.
Owners of early cars with persistent fuel smells who cannot resolve the issue at the sender seal or filler hose level should consider that the tank itself may be the source. Three tank specifications are catalogued: the early single-skin tank for MGF to VIN YD522572, the first double-skin tank for MGF from VIN YD522573 to MG TF VIN 4D634733, and the later complete tank-and-pump assembly for MG TF from VIN 4D634734 onwards.
Electric Fuel Pump
The fuel pump is a submerged electric unit mounted through a flange in the top of the tank, incorporating the fuel level sender float and arm. The pump primes the system for a few seconds when the ignition is first turned on, then runs continuously while the engine runs, maintaining fuel rail pressure via the regulator which returns excess fuel to the tank. Three fuel pump assemblies match the three tank variants across MGF and MG TF production, early MGF, MY2000-onwards MGF and early MG TF, and later MG TF.
When replacing the pump, the correct variant for the VIN must be specified; fitting a pump intended for a different production window can produce sender calibration errors (wrong fuel gauge readings) even where the pump itself physically fits. The fuel pump flange seal is a separate item and must always be renewed whenever the pump is disturbed, the later specification seal cross-fits MG ZT applications from 2001 onwards.
Fuel Pump Failure, The Hot-Start Symptom
The signature failure pattern for an MGF or MG TF fuel pump is difficult hot starting. A marginal pump delivers enough pressure for cold starting and light-load running, but loses output as under-bonnet temperatures rise, and when the car is stopped briefly (at fuel station, shop, or short-distance errand) the pump struggles to maintain sufficient pressure for a clean restart.
Owners often notice this as a gradual progression: one or two warm-weather incidents become a weekly occurrence, then every warm restart. Before condemning the pump, the fuel pump relay, wiring, and inertia switch should all be checked, a tired relay produces identical symptoms to a tired pump. Pump replacement involves dropping the cooling system, removing the access panel, and lifting the pump assembly out through the flange opening; it is a workshop job of several hours rather than a quick roadside fix.
Inertia Safety Switch
The inertia switch is a crash-protection device that cuts power to the fuel pump circuit in the event of a collision. A single specification fits all MGF and MG TF cars, mounted in the engine bay. The switch trips from a significant impact (typically at the forces associated with a collision that would deploy airbags) and can also be triggered by a dropped jack, a heavy kerb strike, or other shock loads that are not actual collisions. A tripped inertia switch presents as "car cranks but will not start", the pump receives no power, so no fuel pressure is developed.
The switch is reset by pressing the button on top; if pressing resets the switch and the car starts normally, no further action is needed. Repeated unexplained trips indicate a failing switch that should be replaced, as it introduces the possibility of the car cutting out at inappropriate moments.