Fuel tank & fuel system

How it works

The tank stores fuel and feeds it to the carburettor or injection pump. It must be able to breathe: as fuel is used, air has to get in, through a vent in the cap or a breather hose. If the vent is blocked, a vacuum builds up and the engine runs out of breath and dies after a few kilometres, then restarts once the cap is opened. Many modern bikes capture fuel vapour in a charcoal canister. The inside of a steel tank can rust, especially if the bike is stored with little fuel: rust clogs filters and jets. Water can also collect through condensation. A bike stored for a long time is best kept with a full tank and a fuel stabiliser. Fuel hoses age and crack: any smell of petrol must be taken seriously.

Maintenance tips

• ✓If the engine dies after a few kilometres and restarts once the cap is opened, check the tank vent.
• ✓For long storage, fill the tank and add a fuel stabiliser to limit rust and condensation.
• ✓Inspect fuel hoses and clamps regularly: replace anything cracked.
• ✓A persistent smell of petrol is a fire risk: find the leak before riding.
• ✓A tank rusty inside can be treated (de-rusting, sealant) or replaced; fit an in-line filter in the meantime.