Evaporative Emissions System: Testing and Inspection

Evaporative Canister Location (Typical):

VISUAL INSPECTION
1. Check condition and routing of vacuum hoses. Refer to Vehicle Emission Control Information (VECI) label, (underhood).
2. Ensure all vacuum hoses and electrical wires are clear of exhaust manifold to prevent deterioration. Due to temperature, vacuum hoses should always be a minimum of three inches from exhaust manifold.

NOTE: Use only fuel resistant hoses when servicing the evaporative control system.

Canister Purge Solenoid:

CANISTER PURGE SOLENOID TEST
1. Disconnect Solenoid electrical connector, and apply vacuum. Using two jumper wires, energize the solenoid by connecting one of the solenoid terminals to ground, and the other terminal to battery positive.
- A "click" should be heard as voltage is applied to terminal.
- Vacuum should hold when voltage is applied, and bleed off when disconnected.
2. Disconnect jumper wires.
3. Measure resistance between Purge Solenoid terminals.
- Resistance should be between 36 and 44 ohms.
4. If solenoid failed any test, replace solenoid. See COMPONENT REPLACEMENT AND REPAIR PROCEDURES.

SOLENOID CONTROL CIRCUIT TEST
1. Disconnect vacuum hose from solenoid to throttle body at throttle body and plug nipple.
2. Connect vacuum pump to open end of hose.
3. Ensure that engine coolant temperature is less than 140°F (60°C). Start engine and allow to idle.
4. Apply 15 in. Hg vacuum and verify that it holds.
5. Increase engine speed to 3000 rpm, verify vacuum is still held.
6. Allow engine to warm up until the coolant temperature is above 158°F (70°C). Increase engine speed to 3000 rpm (within three minutes of starting the vehicle) apply vacuum. Vacuum should not hold.
7. Let engine return to idle and apply 15 in Hg vacuum. Verify that vacuum holds.
8. Allow engine to run longer than 3 minutes and increase speed to 3000 rpm. Apply 15 in. Hg vacuum. Verify that vacuum holds momentarily then bleeds off.

NOTE: If solenoid fails any test, check connections, and perform actuation test using scan tool.

Vapor Canister Hose Connections:

CHARCOAL CANISTER CONTROL VALVE TEST
1. Disconnect 3/16" vacuum hose from canister and connect a vacuum pump to nipple.
2. Apply 10 inches of vacuum.
3. If valve does not hold vacuum, replace canister.