It is beneficial to fill your tank once it gets to 1/4 full. There are two reasons for this. Air contains moisture the more air in the fuel tank the more moisture in the fuel tank. Secondly the fuel pump uses the fuel to help cool itself. The less fuel the more chance the fuel pump will overheat which will shorten it's life.
If the gas isn't leaking while the engine is running and you have half a tank, then the problem is with the fuel tank itself. You either have a hole in the upper half of the tank, or the gasket for your fuel sending unit is leaking.
The cost to fill a gas tank in a van will depend on the rice of gas. The higher the price of gas, the more it will cost to fill the gas tank. You will need to know how many gallons it takes to fill the tank and the price per gallon of fuel. You do the math.
Fill up your gas tank, drive for 1/2 tank. Refill your gas tank, and take the amount of gallons put in and divide it by the miles driven on that half tank. This will give you your average MPG. Example: I just drove for 125 miles, now i am at a half tank. When I'm done putting gas in, i write down that it took 5.43 gallons to fill. I divide 125 by 5.43 and get 23mpg.
Check the filler cap gasket to see if it is worn out or torn.
you fill gas in it
I do not understan your question. You cannot fill up an empty gas tank? Is that what you are saying?
it is likely your fuel gauge is not working properly
One is for the fill line to put gas in, the other is probab;y for the sensor to tell how mush gas is in the tank.
If it seems as though you cannot get the tank to fill completely on an 01 Sienna, it is likely that your gas gauge is not working properly. You are probably actually getting the tank full of gas.
At about $3.10 per gallon, it will cost $12.75 to fill the tank.
Bad fuel fill.
It depends on gas prices and how much gas you have in your tank.