EVAP System Check

If the system fails the purge flow test or flows very little, the following Evaporative Emission System Check may help identify problems causing no or low purge flow. The following inspection procedures are for a '95 5S-FE Camry:

1. First, visually inspect the fuel tank, fuel cap, canister, lines and connections for any damage, cracks, fuel leakage, or deterioration and repair or replace as necessary.

2. Check the canister for a clogged filter or stuck check valve by performing the following:

• Apply low pressure compressed air (0.68 psi) into the fuel tank vapor port (port A) of the canister and confirm that air flows out from all other canister ports.

Note: Airflow from canister ports is difficult to detect.

Fuel Tank

EVAP System Check

Vapor Port

(Port A) —-wrv

Compressed Air ^gjg

Purge Port

J^-(Port B)

F"!

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• Next, apply low pressure compressed air to the purge port (port B) of the canister and confirm that air does not flow out from any of the other ports.

Note: Replace the canister if a problem is detected with either of the checks above.

• Clean the canister filter by applying air pressure (43 psi) to the tank vapor port (port A) while holding the purge port (port B) closed with your finger.

Note: If carbon blows out during this test replace the canister.

Fuel Tank

EVAP System Check

Vapor Port

(Port A)

Compressed Air //"|sjl§

Purge Port

J^-(PortB)

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3. Check the operation of the TVV by performing the following:

• Disconnect the hoses from the TVV and then attach a hand operated vacuum pump to the lower port of the TVV.

• With coolant temperature cold (below 95'F), operate the vacuum pump and confirm that air does not flow (vacuum is held) from the upper port to the lower port.

Note: It is normal for some TVWs to allow a slight amount of airflow when cold.

• Next, allow coolant temperature to rise above 129' F. Operate the vacuum pump and confirm that air now flows (vacuum bleeds off) between the top port and the lower port.

Note: If the TVV fails any of the checks above, replace it.

This EVAP check example systematically confirms the integrity of the evaporative canister and TVV. Once repair or replacement is made, retest the system to confirm sufficient purge improvement needed to pass a retest. Because slight variations exist between evaporative system tests, refer to the Repair Manual for specific EVAP test procedures and specifications.

Do It Yourself Car Diagnosis

Do It Yourself Car Diagnosis

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