Question 1

What is the purge/seal EVAP system?

Accepted Answer

The most common EVAP system used on cars today

Question 2

How does the purge/seal EVAP system work?

Accepted Answer

Fuel vapors are stored in the fuel tank and the vapor canister. When conditions are correct, the engine control module opens the purge solenoid allowing engine vacuum to draw stored fuel vapor from the EVAP system into the engine and burns them with the air/fuel mixture.

Question 3

How does the ECM test for EVAP leaks?

Accepted Answer

Understanding how the vehicle tests for leaks can aid in the accurate and efficient diagnosis of the purge/seal EVAP system.

Question 4

What are common purge/seal EVAP checks?

Accepted Answer

Inspect for loose gas cap
Visual inspection of hoses for cracks, leaks and proper routing and attachment
Using a scan tool or multi-meter, check key-on, engine-off (KOEO) FTP sensor voltage for proper reading
Using a full function scan tool, perform an EVAP system leak test to verify failure is present
Verify proper purge solenoid functionality
Verify proper vent solenoid functionality
Perform a system leak test using a smoke machine

Question 5

What are the purge/seal EVAP components?

Accepted Answer

Fuel tank
Vent Solenoid
Fuel Filler Neck
Fuel lines/hoses
Purge solenoid
Fuel Tank Pressure Sensor
Charcoal canister
Gas cap