why does my volvo smell like gas when istart it up and run the fan?

Check the fuel lines under the hood. Look for stains where the steel and rubber lines join. Sometimes the fuel pressure regulator fails and will leak so check that too. If you don't see anything, turn the key to "On" to run the pump - don't start the engine. Go back to see if any there any strong smells or fresh stains.

Almost certainly the fuel rail for the injection system. Look for a leak, when the engine is running, at the front end - that's where mine was. I have read in other forums that this cannot be repaired by JB Weld, but that is how I repaired mine almost 6 months ago and it is still good. My leak was so bad it was making me ill. I now get an extra 5 miles per gallon. Good luck!