System Diagnosis - EVAP - Turbo

CANISTER PURGE FUNCTIONAL TEST

TEST DESCRIPTION:

1. Apply a short length of hose to the lower tube of purge valve and blow air into it. Very little air should pass into canister, if any at all. If the canister has a constant purge orifice a small amount of air may go into canister. If air passes into canister, replace canister. If air does not pass into canister proceed to the next step.

2. Use a hand held vacuum pump and apply 15" Hg or 51 kPa of vacuum to the tube labeled "CONTROL VAC" on the purge valve diaphragm cover. The diaphragm should hold vacuum for at least 20 seconds. If it does not, replace the canister. If it does hold vacuum, proceed to the next step.

3. With vacuum still applied to the control vacuum tube, blow air into the lower tube. If air flow increased into the canister, the purge valve is OK. If air flow does not pass into the canister, the purge valve is bad and the canister must be replaced.




INCORRECT OPERATION MAY CAUSE:

1. Poor idle, stalling and poor driveability. Check for:

a. Inoperative or defective purge valve or solenoid
b. Damaged canister
c. Hoses split, cracked or not connected to the proper tubes
d. Pinched or plugged hose(s).




2. Evidence of fuel loss or fuel vapor odor. Check for:

a. Liquid fuel leaking from fuel lines, fuel pump, or injectors
b. Cracked or damaged canister
c. Inoperative canister control valve
d. Disconnected, misrouted, kinked, deteriorated or damaged vapor hoses, or control hoses
d. If the solenoid is always open, the canister may purge all the time. This can allow extra fuel at idle or during warm-up, which can cause a rough idle or a rich operation
e. If the solenoid is always closed, the canister can become over-loaded, resulting in fuel odor.