just wondering - does a 92 jimmy vin w - have an evap system or a purge valve - i know older and even newer models do but i haven't come across anything for this year of jimmy.

'92 does have a purge canister and a purge solenoid. OBDI does not monitor, and therefore cannot turn on the service engine soon light if there is a malfunction in the EVAP system. All OBDII equipped vehicles monitor the EVAP system.

thanks for the info - i have searched everywhere for it - any idea where i might find it ?

okay im jus-a-little blind -- found it under the airbox - i kinda thought it was strange that my truck wouldn't have one - thanks .

There is a filter in the canister that is replaceable. Most auto parts stores have them and they run about $2. Probably 3 vacuum lines connected to the canister. One goes to the top of the fuel tank. When the engine is off, fuel vapors travel to the canister. The second line goes to manifold vacuum, and the third goes to ported vacuum, most likely through a PVS. The canister is purged when vacuum is applied to the third line after the engine has reached operating temperature and the throttle is off idle. The stored vapors travel from the canister to the manifold vacuum source and are burned.

A common problem is the canister will get saturated with liquid fuel. This happens when the fuel tank is "topped off" after the pump shuts off while fueling. The canister is not designed to handle liquid fuel and generally will trip a rich fuel code. Make sure the line going to the tank is clear, (no liquid fuel in it).