Evaporative Emission (EVAP) Canister Purge System Inspection
Caution: Do not breathe the air through the EVAP component tubes
or hoses. The fuel vapors inside the EVAP components may cause personal injury.
Important: Perform a careful visual inspection of the Evaporative Emission (EVAP)
system components and connecting hoses before diagnosis of an EVAP system
malfunction.
Important: The EVAP canister purge system does not perform purging (vacuum is not
detected at the purge hose) unless the engine is sufficiently warmed up and
the Heated Oxygen Sensor (HO2S) is fully activated. When the purge hose is
disconnected as in step 6, some air may be drawn into the purge line. As a
result, the PCM might detect a change in the purge gas concentration and stop
purging. This is a normal action and may be the cause of a failure to detect
vacuum in step 7. If no vacuum is felt in step 7, continued testing of the
EVAP system may be necessary to avoid replacement of good parts.
Failure of the Evaporative Emission (EVAP) Canister Purge System to
pass any of the above checks indicates a possible malfunction that will require
further inspection.
- Allow the engine to cool to room temperature.
- Start the engine (cold).
- Disconnect the purge hose from the EVAP canister.
- Place a finger against the end of the disconnected hose and check
for vacuum. Vacuum should not be felt when the engine is below normal operating
temperatures.
- Connect the purge hose to the EVAP canister and warm the engine
up to normal operating temperature.
- Disconnect the purge hose from the EVAP canister.
- Place a finger over the disconnected hose and check for vacuum.
Vacuum should be felt with the engine running at normal operating temperature.
Evaporative Emission (EVAP) Canister Inspection
- Disconnect the vacuum
hoses from the EVAP canister.
- Blow air into the tank pipe of the EVAP canister. There should
be no restriction of air flow through the purge pipe and the air pipe.
- Replace the EVAP canister, if the EVAP canister fails the above
check.
- Connect the vacuum hoses to the EVAP canister.
Evaporative Emission (EVAP) Canister Purge Valve Inspection
- Disconnect the EVAP Canister
Purge Valve electrical connector.
- Using a DMM (1), measure the resistance of the EVAP Canister Purge
Valve (2) between both terminals. The resistance should be 28 to 36 ohms
at 20°C (68°F).
- Replace the EVAP Canister Purge Valve if the resistance is not
28 to 36 ohms at 20°C (68°F). If the resistance is within specification,
proceed to step 4.
- Disconnect the EVAP Canister Purge Valve vacuum hoses from the intake
manifold and the vacuum pipe (from EVAP canister).
- Blow air into the EVAP Canister Purge Valve vacuum hose that was
disconnected from the vacuum pipe. Air should not pass through the EVAP Canister
Purge Valve and exit from the intake manifold hose.
- Connect 12 volts DC to the EVAP Canister Purge Valve terminals.
- Blow air into the EVAP Canister Purge Valve vacuum hose that was
disconnected from the EVAP canister. Air should pass through the EVAP Canister
Purge Valve and exit from the intake manifold hose.
- Replace the EVAP Canister Purge Valve, if the EVAP Canister Purge
Valve failed this inspection.
- Reconnect the EVAP Canister Purge Valve vacuum hoses and electrical
connector.
Evaporative Emission (EVAP) Canister Vent Solenoid Inspection
- Disconnect the EVAP Canister Vent Solenoid valve electrical connector.
- Using a DMM, measure the resistance of the EVAP Canister Vent
Solenoid valve between both terminals. The resistance should be 25 to 30 ohms
at 20°C (68°F).
- Replace the EVAP Canister Vent Solenoid valve if the resistance
is not 25 to 30 ohms at 20°C (68°F). If the resistance is within specification,
proceed to step 3.
- Disconnect the EVAP Canister
Vent solenoid hose from the EVAP canister.
- Blow air into the EVAP Canister Vent Solenoid hose that was disconnected
from the EVAP canister. Air should pass through the EVAP Canister Vent Solenoid.
- Connect 12 volts DC to
the EVAP Canister Vent Solenoid terminals.
- Blow air into the EVAP Canister Vent solenoid vacuum hose that
was disconnected from the EVAP canister. Air should not pass through the EVAP
Canister Vent Solenoid and exit from the other end.
- Replace the EVAP Canister Vent Solenoid, if the EVAP Canister
Vent Solenoid failed this inspection.
- Reconnect the EVAP Canister Vent Solenoid valve vacuum hoses and
electrical connector.
EVAP Tank Pressure Control Solenoid Vacuum Valve Inspection
- Disconnect the EVAP Tank Pressure Control Solenoid vacuum valve
electrical connector.
- Using a DMM, measure the resistance of the EVAP Tank Pressure
Control Solenoid vacuum valve between both terminals. The resistance should
be 28 to 36 ohms at 20°C (68°F).
- Replace the EVAP Tank Pressure Control Solenoid vacuum valve if
the resistance is not 28 to 36 ohms at 20°C (68°F). If the resistance
is within specification, proceed to step 4.
- Disconnect the EVAP Tank
Pressure Control Solenoid vacuum valve vacuum hoses from the intake manifold
and the vacuum pipe (from the Tank Pressure Control valve).
- Blow air into the EVAP Tank Pressure Control Solenoid vacuum valve
vacuum hose that was disconnected from the vacuum pipe. Air should not pass
through the EVAP Tank Pressure Control Solenoid vacuum valve and exit from
the intake manifold hose.
- Connect 12 volts DC to the EVAP Tank Pressure Control Solenoid vacuum
valve terminals.
- Blow air into the EVAP Tank Pressure Control Solenoid vacuum valve
vacuum hose that was disconnected from the vacuum pipe. Air should pass through
the EVAP Tank Pressure Control Solenoid vacuum valve and exit from the intake
manifold hose.
- Replace the EVAP Tank Pressure Control Solenoid vacuum valve,
if the EVAP Tank Pressure Control Solenoid vacuum valve failed this inspection.
- Reconnect the EVAP Tank Pressure Control Solenoid vacuum valve
vacuum hoses and electrical connector.
Tank Pressure Control Valve Inspection
- Connect a length of the
hose to the Fuel Tank Pressure Control valve vacuum port marked TANK.
- Blow hard into the hose. Air should pass slowly through to the
side marked CAN of the Fuel Tank Pressure Control valve (1).
- Remove the hose from the TANK side and connect it to the CAN
side of the Fuel Tank Pressure Control valve.
- Blow easily into the hose. Air should pass through to the side
marked TANK of the Fuel Tank Pressure Control valve (2).
- Use a
J 23738-A
hand
vacuum pump in order to apply the vacuum to the vacuum port.
- With vacuum applied, blow into the hose marked TANK. Air should
pass easily through to the side marked CAN of the Fuel Tank Pressure Control
valve (3).
- If the Fuel Tank Control valve fails any of the above checks
replace the Fuel Tank Pressure Control valve.