2004 Sierra fuel cap

[smokyjoeko]

Hi everyone I have a 2004 GMC Sierra. The TIGHTEN FUEL CAP message comes on for a short time then goes out. After the message comes on a couple times the engine light will come on the next time I start the truck. The engine light goes out after driving a short distance. (1 to 5 miles)
I have replaced fuel cap and trouble is still there. What should I check next?
Thanks

 

[smokyjoeko]

I check condition of hoses. Didn't find any that looked bad. Broke down and took to dealer. They replaced vent valve. $353.00 working ok now.

 

[Halftrack]

Where is vent valve located?? I have same problem...

 

[smokyjoeko]

Sorry its taken me so long to reply. Must be on fuel tank. They said fuel tank had to be lowered to work on it. A short hose with what looks like a filter has also been added. Again sorry.