7-3 Fuel Tank Venting

Fuel Tank Pressure/Vacuum Conditions
All Vapour Canister Models TR6/Spitfire

BritCar ServiceConditions of pressurization and vacuum within the fuel tank can result in very unstable fuel delivery conditions and carb fuel flooding and starvation on models with closed circuit/vapour canister tank venting. Extended cranking times following overnight parking, stalling, or overly rich/flooding conditions may result. In extreme circumstances, complete collapse of the fuel tank may result.

The most frequent cause of this fuel tank condition is a plugged restrictor in the vapour line to the charcoal/purge canister. This restrictor can be located in the vapour line the runs to the fuel tank from the canister. It is a brass fitting that fits in the line and usually located in-line 3″ to 4″ from the canister. This restrictor has a small drilling (0.015″ ca) in the center that can plug from corrosion and varnish. This restrictor must be clear. Do not enlarge the drilling as it is functional with the anti run-on system and fuel tank over-fill control.