Fumes enter when outside vents are open. Toyota could not find problem.

Your car has a small purge valve called a purge solenoid that controls the venting of fumes from the fuel tank as these fumes build up inside, particularly when you are refueling the car with gas. The EVAP system prevents fuel vapors from the fuel tank from escaping into the atmosphere. ... Normally the vent valve is open.

If you are talking about the air bleed screw on the tank cap it should be open when the motor is running and close when it is not. This allows the tank to vent when you are travelling and when you are not prevents petrol fumes for becoming a problem in the bottom of the boat.

The exhaust inside the car would suggest the vents in question have fallen apart somewhere in the dash between the engine compartment and the interior allowing fumes to enter the cabin. Get that checked at a garage right away. Very dangerous to breath exhaust fumes.

It has a separate recirulation button, press this and it recirculates the inside air and stops the outside air from coming in,

Since EPA regulations say a car can't let gas fumes into the air the vent valve opens to let air enter the fuel tank so it won't collapse when the fuel is removed to run the engine. It closes when there is pressure above atmospheric pressure so the gas fumes can't come out

I emphasize with you on this problem. If you are smelling fumes you are inhaling car "exhaust" which is extremely dangerous as you know. I have a 1999 Passat that had a "fume" issue that baffled me for over a year. Your description of the conditions that you smell the fumes may not be complete enough for me to definitively say what your problem is but I will tell you what I experienced and discovered on my car. I only smelled the fumes when my heat or AC was on and the car was NOT moving forward. Also, if the AC recirculate button was on I didn't smell the problem as bad. So, what I found was that the car's emission control piping was leaking the exhaust fumes that bypass the pistons and go into the crankcase. These fumes are normally piped back into the intake manifold to be re-burned to reduce emissions. With a completed disintegrated rubber emissions pipe coming off the engine block, the fumes entered into the engine compartment which is sealed from the interior of the car. So, how did the fumes get in my car? Well, when waiting at a red light and with the heat or AC on (no recirculate) the fumes would fill the engine compartment and overflow out the wheel wells and wrap over the hood to the intake vents (near the wiper blades) of the car's interior air system. If the recirculate button is pressed with the AC on, the car's interior air (no exterior air) is recirculated inside the car to cool it faster and I didn't smell the fumes as bad. Also on windy days the fumes didn't get a chance to wrap over the hood and get into the intake vents. Because of the unique conditions that had to occur in order to smell or not smell the fumes it was a difficult problem to solve. By the way, the disintegrated rubber pipe was almost impossible to see and there is no real reference material to read that describes the location and depiction of the emissions plumbing. I hope this helps you!

Three things come to mind. You may have an exhaust system leak. Or, the rear hatch is not closing good, or not sealing properly, allowing exhaust fumes to enter the rear compartment. If you drive with the rear windows open, the exhaust fumes will be drawn into the vehicle while the vehicle is moving. Just some ideas on where to look for the source of the fumes. Don't take the problem lightly. The fumes can be deadly, or at the very least, make you ill.

This issue is caused by crankcase pressure issue.
Normally filtered air enters the engine, runs through the crank case and then is pulled into the intake through the PCV valve. Durning hard acceleration, the PCV valve closes (to prevent explosion of fumes in crank case and blowing valve covers and pan off) and the PCV system reverses, with fumes coming back through the filtered intake.

Usually there is minimal oil that gets back into the air cleaner.

So, when somthing goes wrong, like excessive blow by, for example, the crankcase pressure overcomes the PCV valve and intake of fumes capability, and oily starts showing up in the air filter.

Investigate the crankcase pressure and PCV system.

If you have petrol smelling inside the car you probably have an open area of the car's body that permits outside air to enter. is the smell greater in the front or back? This is not easy to fix as you have to locate exactly from where the leak comes from by smelling and following to the source. In the engine compartment there is a small filter that vents fumes from the tank to prevent explosion of the tank due to increase in pressure as the car moves. At the tank section that might be a broken vent hose.

THe blend door seems to be stuck. When you change settings from defrost to floor air or, vent, the blend door opens and closes directing the air to the place you want it to go to. I have had some success spraying a lubricating oil such as WD40 under the dash on the blend door. You need to get under the dash with a flashlight to locate it. It looks like a flap. Spray it with a couple of shots of the WD40. Go easy on the spraying as you may be inhaling the fumes. Keep the doors and windows open to minimize the fumes. Wait about 1/2 hour and try the A/C functions. (defrost, floor, vent air)