F 350 4WD Pickup V8-351 5.8L VIN H EFI (1997)
Canister Purge Solenoid: Description and Operation
Canister Purge Solenoid (CPRV)
- Used with closed loop
- Normally closed, solenoid vacuum valve
- Purges on signal from Powertrain Control Module (PCM), usually at warm and hot cruise
The evaporative emission canister purge valve is located in the vapor tube between the evaporative emissions canister and the throttle body, and is
normally in the closed position until electrically energized.
The operation of the evaporative emission canister purge valve is controlled by the Powertrain Control Module (PCM). When the engine is OFF, the
purge valve is not energized and is in a closed, nonflowing condition. When the engine is running, the PCM reads engine rpm, engine load, engine
temperature and other variables, and decides the proper time for the engine to accept fuel vapors. When this occurs, the purge valve is energized,
allowing flow from the evaporative emissions canister to the intake manifold.
The vapors are then consumed in the engine. This action purges the evaporative emissions canister of fuel vapors. It occurs as fresh air is sucked into the
evaporative emissions canister under the fresh air inlet cap of the evaporative emissions canister and through the activated carbon bed. This allows the
stored fuel vapors to pass from the evaporative emissions canister through the evaporative emission return tube and the evaporative emission canister
purge valve, and into the engine.
