Where is the Vapor Canister Vent Solenoid located on a 2003 Chevy Silverado 1500, 4.3L engine? And do you ave to remove the pick-up bed to access it, if it is on top of the tank?

Have you changed your fuel cap? That is usually the culprit. If that doesn't solve your issue, a simple smoke test will show you where the system is leaking.

Under car,usually mounted near or in front of gas tank

https://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd=7&cad=rja&uact=8&ved=0ahUKEwiWp7rZtOfKAhVBlh4KHY1RAwYQtwIINTAG&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DQIlti3aZ22M&usg=AFQjCNEz4TLhC8cVKeIar-IctwksFPqv_g Repair Guides Components Systems Evaporative Emission Control System... https://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd=11&cad=rja&uact=8&ved=0ahUKEwjQ4dL_tOfKAhVCGx4KHaITC3w4ChAWCBowAA&url=http%3A%2F%2Fcommunity.cartalk.com%2Fdiscussion%2F2290225%2F01-olds-alero-evap-problem-getting-choked-out-by-gas-fumes&usg=AFQjCNEyLR6NegYlup_S2N6z_mGccu_DFA&bvm=bv.113370389,d.dmo

HERE'S WHAT IT LOOK'S LIKE.Mounted near evaporative canister. http://www.autozone.com/engine-management/canister-vent-valve-solenoid/dorman-canister-vent-valve-solenoid/kia/sorento-2wd/2004/6-cylinders-3-3-5l-mfi-dohc/970779_548862_0

Your best bet would be to obtain a small service manual ...Chiltons still prints them. They are available at just about every major autoparts store and run about $25 - $30 or so. You'd probably have to order it for your '03. Or look on Amazon. Another source for step by step "how to" is AutoZone's website. The beauty of the manuals are the pictures. They will show you where the vent valve is ...because there's a good chance it isn't on the canister. And the canister itself can be hidden away under some other piece of gear in the engine bay. A manual will also give you heads-up to any special considerations or procedures when doing the work. A picture's worth a thousand words but you could print a thousand words and still not paint the right picture. Get the book.

On a 2002 Sunfire, the fuel vapor canister purge solenoid (AKA canister vent solenoid) is between the engine and the firewall, up high near the hood. It's a black box with two hose or fuel vapor line ports going toward the passenger side and one toward the driver side. One of the passenger side hoses goes to the vapor canister.

Hello have a 2006 Isuzu I-280 and I needed to replace, at this moment, the Evaporative Valve Soleniod which is instaled next to the Vapor Canister. In my case, It is mounted on the frame behind the gas tank you will have to move the spare tire out of the way one bolt holds it in place, this is where the canister is and the valve is mounted on the canister this is where it is mounted on my 2006 I-280. If you need to replace the solenoid and you can't find the original Isuzu part, you can ask for the 2006 Chevy Impala V-6 3.5 Purge Valve Solenoid. It is the same piece. The old Evaporative Vent Valve Solenoid has a number part PA-GF30, and it is the same part number I found in the new Chevy Impala Evaporative Vent Valve Solenoid. Good luck.

It is located under the car near the gas tank on a tray with the fuel vapor storage cannister

If you have a local AutoZone close...go there and let them plug in the OBIS3. Not only will it tell you the same things you have shown here...ask them how to fix to check the issues. They will give you a print out that will help walk you through it.

Semper Fi,
Z

DTC P0446 Evaporative Emission (EVAP) Vent System Performance

The vehicle control module (VCM) monitors the performance of the evaporative emission (EVAP) system by applying a predetermined level of vacuum to the EVAP system and monitors the vacuum decay rate. The VCM sets this diagnostic trouble code (DTC) if the vacuum decay rate is more than a predetermined value. The VCM monitors the amount of vacuum and the amount of pressure in the EVAP system by monitoring the fuel tank pressure sensor. For this DTC, the VCM turns ON both the EVAP purge valve and the EVAP vent valve when the Conditions for Running the DTC are met. This applies an engine vacuum to a closed EVAP system. The VCM turns OFF both the EVAP purge valve and the EVAP vent valve when the system reaches a correct amount of vacuum. The EVAP system should quickly RELEASE the vacuum in the EVAP system with the EVAP purge valve OFF and the EVAP vent valve OFF (open). This test indicates a blocked or restricted EVAP vent path if the EVAP system fails to release the vacuum quickly enough.

Continuous Memory Diagnostic Trouble Code (DTC) P0442 indicates that a fuel vapor leak has been detected [as small as 0.10 cm (0.04 inch)] in the Evaporative Emission (EVAP) system.
Note: Prior to performing the following diagnosis inspect the Canister Vent Solenoid (CV) for contamination. A situation may exist where contamination holds open the Canister Vent (CV) solenoid enough to set DTC P0442 and also plugs the port to atmosphere enough to keep system from being vented quickly.

• After market parts and accessories nonconforming to the EVAP system specifications.
• Damaged, cross threaded or loosely installed fuel filler cap.
• Small holes or cuts in fuel vapor hoses/tubes (EVAP canister tube, EVAP canister outlet tube or EVAP return tube) in the EVAP system.
• Loose fuel vapor hose/tube connections to EVAP system components.
• EVAP system component [EVAP canister purge valve, fuel tank pressure (FTP) sensor, canister vent (CV) solenoid, fuel vapor control valve tube assembly or fuel vapor vent valve assembly] seals leaking.
• CV solenoid partially open when commanded closed.
• EVAP canister leaking.
• Check for presence of fuel filler cap.
• Verify that the CV solenoid is properly seated on the EVAP canister (if possible).
• Visually inspect for cut or loose connections to fuel vapor hoses/tubes in following locations:
  • EVAP canister to EVAP canister purge valve.
  • EVAP canister to fuel vapor vent valve assembly.
  • fuel vapor control valve tube assembly to fuel tank (if applicable).