EVAP Purge Flow Monitor Failure

NAME OF CODE
EVAP Purge Flow Monitor Failure

WHEN MONITORED
With engine temperature greater than 170° F, engine is in closed loop, engine idling for 2 minutes, no Power Take Off (PTO) in use, no low fuel, vacuum greater than 0.7 inches mercury, and barometric altitude less than 8,000 feet.

SET CONDITION
Note: with Leak Detection Pump (LDP): must pass stricter evap system test first. No air flow through the evaporative system is detected by the evap monitor.

THEORY OF OPERATION
The purpose of the evaporative system is to recycle the accumulated fuel vapor bound in the fuel tank. The fuel vapor is temporarily held in the evap canister and is recirculated via the evap solenoid through the air intake system and consumed during combustion. The evaporative system consists of the fuel tank, vapor flow control orifice, evap solenoid, and evap canister connected by a series of rubber noses and plastic connectors.

POSSIBLE CAUSES
- Rubber hose(s) pierced, cut, cracked, kinked or off (solenoid to throttle body)
- Plastic connector to evap solenoid cracked
- Evap solenoid malfunction
- Hose plugged from solenoid to canister
- Hose plugged from throttle body to solenoid
- Connector terminals
- Connector wires