I have been hearing a strange clicking sound and was fearing that it was a lifter or something in the valve area... Well, while checking for vacuum leaks I accidentally located the source of the sound.  It is apparently coming from a little solenoid that looks like it could be the charcoal canister purge... when the engine is revved, it clicks LOUDLY on and off. So, I unhooked it and voila, no more noise! Anyone know if this is important to keep connected?

 

mallard75,  that is  the evap cannister purge valve. Its for emissions but I'm not how important it is.  It may cause an emissions problem.  Here is how to test it.

WARNING: Do not suck air through the Evaporative Emission (EVAP) canister purge valve tubes/hoses. Fuel vapor inside the EVAP canister purge valve is harmful .

Tool Required Digital multimeter   

   1. Disconnect the EVAP canister purge valve electrical connector.
   2. Using multimeter, measure resistance of the EVAP canister purge valve between both terminals. If resistance is not 28 to 36 ohms at 20°C (68°F), replace the EVAP canister purge valve. If the resistance is within specification, proceed with step 3.
   3. Disconnect the EVAP canister purge valve vacuum hoses from the intake manifold and from the EVAP canister.
   4. Blow air into the EVAP canister purge valve vacuum hose that was disconnected from the EVAP canister. Air should not pass through the EVAP canister purge valve and exit from the intake manifold hose.
   5. Connect 12 volts DC to the EVAP canister purge valve terminals.
   6. 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.
   7. If the EVAP canister purge valve failed this inspection, replace it. If the EVAP canister purge valve passed this inspection, reconnect the vacuum hoses and electrical connector.