1994 Toyota Corolla

Hi arlenefranzblau, The only thing that can produce soot and be released at the fuel tank would be the charcoal canister. Perform the following test and if the canister is bad, it has to be replaced. Charcoal Canister Disconnect hoses from charcoal canister. Check for clogged filter and/or stuck check valve by applying low air pressure to port "A". See Fig. 32 . Ensure air flows freely from other ports on charcoal canister. 2. Apply low air pressure to port "B". See Fig. 32 . Ensure no air flows from any other ports on charcoal canister. Replace charcoal canister if defective. 3. To clean charcoal canister filter, apply 43 psi (3 kg/cm 2 ) air pressure to port "A" while holding port "B" closed. Ensure no activated carbon comes out of charcoal canister. DO NOT attempt to wash out charcoal canister. If activated carbon comes out, replace the canister.