Evaporative Emissions System: Testing and Inspection

[1][2]BOWL VENT VALVE TEST

CAUTION:
Let the engine cool before proceeding with this test. If the engine is not cool enough, fuel could gush out from the [1][2]bowl vent valve.

With the engine stopped.
1. Remove the air cleaner.
2. Disconnect the bowl vapor hose from the [1][2]bowl vent valve nipple.

Testing The Bowl Vent Valve:

3. Connect a hand vacuum pump to the [1][2]bowl vent valve nipple.
4. Apply 6.1 in. vacuum to the [1][2]bowl vent valve.
Vacuum should leak.
5. Start the engine and let it idle.
6. Apply 6.1 in. vacuum to the [1][2]bowl vent valve, again.
Vacuum should hold.



CHARCOAL CANISTER

*** UPDATED BY TSB # 18-06-89 April 17, 1989

Test Procedure for hard restart after vehicle is shut-off at high ambient temperatures.
1. Verify condition by driving the vehicle until the engine is fully warm.
2. Shut off engine and remove the air cleaner assembly.
3. Look into throttle bore using a flash light.

If condition is present a puddling of fuel will be seen at the bottom of the intake bore, and the throttle plate will appear to be wet with fuel.

4. If condition is verified, replace the charcoal canister. The new canister will have an identification mark , "1M" embossed on the top of the unit.

Testing The Purge Control System:

PURGE CONTROL SYSTEM

While the engine is stopped and cold [coolant below 50°C (122°F)].
1. Disconnect the black vacuum hose from the intake manifold nipple and plug the nipple.
2. Connect a hand vacuum pump to the disconnected black vacuum hose.
3. Start and run the engine at 2,500 rpm.
4. Apply 15.7 in. vacuum.
Vacuum should be held.

Start and run the engine until it is hot [coolant has reached 95°C (205°F)].
5. While the engine is idling, apply 15.7 in. vacuum.
Vacuum should be held.
6. Increase the engine rpm to 2,500.
Vacuum should leak

Testing The Purge Control Valve:

PURGE CONTROL VALVE

1. Remove the Purge Control Valve.
2. Lightly blow air into canister side nipple. Air should not pass through.
3. Connect a vacuum pump to the vacuum nipple of the purge control valve.
4. Apply 8.0 in.Hg vacuum and lightly blow air into valve from canister side. Air should pass through.
If the valve is not functioning properly, check for a clogged or broken vacuum hose, or a malfunctioning thermo valve.

Testing The Thermo Valve:

THERMO VALVE

NOTE: When disconnecting the vacuum hoses, mark or label them to ensure proper routing when being reconnected.

1. Disconnect the white striped vacuum hose from the thermo valve.
2. Connect a hand vacuum pump to the thermo valve, apply vacuum.
If coolant temperature is below 10°C (50°F) vacuum should leak.
If coolant temperature is above 18°C (65°F) vacuum should hold.

Thermo Valve Test:

3. Disconnect all vacuum hoses from the thermo valve.
4. Connect a hand vacuum pump to nipple (B).
5. Plug the other nipples which are not being tested, and apply vacuum.
If coolant temperature is below 40°C (104°F) vacuum should leak.
If coolant temperature is above 65°C (149°F) vacuum should hold.
6. Repeat the above test for nipples (C) and (D).

Check Valve Testing:

CHECK VALVES
1. Remove the check valve.
2. Connect a hand vacuum pump to the inlet side.
3. Apply vacuum. Vacuum should not leak.
4. Repeat test for other side of valve.
5. Vacuum should leak.