What are the symptoms of a bad charcoal canister?

[SanNathan]

There are two main symptoms when a charcoal canister fails: 1. Difficulty starting the engine (charcoal canister purge valve stuck open): Since the purge valve remains open continuously, the intake manifold becomes filled with fuel vapors. When starting the engine, this overly rich air-fuel mixture can cause starting difficulties or even stalling. 2. Fuel vapor leakage (charcoal canister purge valve stuck closed): When the purge valve remains closed continuously, the stored fuel vapors in the canister cannot be purged. This leads to increased pressure in the fuel tank, eventually causing fuel vapors to leak through the fuel cap's pressure relief valve.