CCV Fitting See Figures 2 and 3 1. With the engine running, remove the CCV fitting. a. If the fitting is not plugged, a hissing noise will be heard as air passes through the valve. A strong vacuum should also be felt when a finger is placed over the fitting. b. Install the CCV fitting. c. Remove the fresh air hose from the air cleaner assembly and loosely hold a piece of paper over the open end of the hose. After allowing about one minute for the crankcase pressure to reduce, the paper should be sucked against the opening with a noticeable amount of force. 2. Turn the engine OFF . Remove the metered orifice fitting, and check for a plugged condition. A clicking noise should be heard to indicate that the valve mechanism is free. 3. If the crankcase ventilation system meets the tests in Steps 1 and 2 above, no further service is required. If not, the CCV fitting must be cleaned and the system checked again. 4. If Step 1c fails when the CCV fitting is cleaned, it will be necessary to replace the molded vacuum hose with a new one, and to clean the metered orifice port. 5. Clean or replace the engine air cleaner filter element with a new one-for more details, refer to the air cleaner procedure located in General Information & Maintenance. Fig. 2: CCV system diagram for 4.0L engine Fig. 3: CCV system diagram for the 2.5L engine Evaporative Emission Control System OPERATION The evaporative emission control system prevents the release of unburned hydrocarbons, from gasoline or gasoline vapor, into the atmosphere. When pressure in the fuel tank is below 3 psi (20 kPa), the pressure relief/rollover valves open allowing fuel vapors to flow to the evaporative canister where they are absorbed by a charcoal mixture. This prevents excessive pressure buildup in the fuel system. Most canisters are equipped with a calibrated orifice at the inlet to the canister.