How critical is it to replace the fuel tank pressure sensor?

What is your question?

My check engine light wouldn't go out after all the recomendations in the manual. So, I took it to a local Chevrolet dealership and code #P0452 was the diagnosis. The dealership gave me a repair estimate of $1200.00 to replace my fuel tank. So, will it damage my engine if I don't have the repair done?? Also, I had a rat's nest on my carburator...they wouldn't show it to me but, where is the carburator???