Tuesday, 25 July 2017

fuel caps and evap

Todays engine  have fuel tanks that vent  back into the engine itself rather than to atmosphere.
In earlier day the vent was simply hung out of the fuel tank  to equalise pressure.
vehicles today  have a closed system that  partly  absorbs metro; vapour and balances atmospheric pressure  through a charcoal canister.
The amount of gases  or vapour drawn through the  canister is dependant on  many things obviously balancing atmospheric  pressure with out  overichening fuel mixture.
Blocked charcoal canisters and leaky pipes or non operative  evap valves are the common failures.
Any issue with the evap can cause issue with engine power and need looking at.
If when you release your fuel cap there is a n intake of air  you definately have issues even without a code or light appearing