The gasoline smell inside of the car would be a separate issue from your heat. But I strongly suggest you have that checked immediately. Because that could be coming from exhaust gases, and it'll kill you, for sure!
As for your heat, you definitely have air in your system. Because you have heat during start-up and on acceleration, you can eliminate any mechanical failures in your climate control/cooling system.
Now you have to figure out why air is entering your cooling system.
Here is a list of possible causes:
Leaking water pump
leaking intake gasket
blown head gasket
To check for external leaks, run your engine until it reaches operating temp. Then look around on the ground for any anti-freeze. Also look under the hood around the engine for any signs.
If you don't have any external leaks, then it's internal. (Blown head gasket or intake gasket)
Remove your oil dip stick. If your oil looks white, like a milk shake, then your intake gasket is blown. If not:
Take the cap off of your surge tank (While cold), throttle the engine to at least 1,500 r.P.M.S. Look inside the surge tank for large air bubbles. If you see any, it's a blown head gasket.
Wednesday, January 13th, 2010 AT 9:28 PM