Re: collapsed fuel tank
Originally Posted by Irving3
I think collapsed is the correct term and it is the one the service manager used. It is almost flat. I have pictures of it still in the car. The dealer thinks a vacuum caused it and they think the purge valve caused the vacuum but they say they have never seen this before and are not sure the purge valve was the problem.
Fuel pressure at the injectors is maintained at 54-61 psi by the fuel pressure regulator valve. This means that the fuel pump can create a vacuum of at least the same amount. Apply that pressure to a square foot and you have a minimum of 7,776 lbs. I doubt that was the pressure that caused it, I expect that it weakened slowly and totally failed (collapsed) when you heard the splashing gas in the tank when the baffles which provided reinforcement to the tank structure gave way. When the tank was full the gasoline supported the structure, as it is not easily compressed, but as the gas was used the vacuum grew until the tank structure could not take the load.
A partial vacuum is kept in the tank to evacuate the gas vapors. The vacuum has to be relieved so that it does not reach catastrophic levels but this system failed. With check valves in the system to prevent fuel returning to the tank its volume had to be replaced. Whatever lets air into the tank failed, and why did the car run rough when it had air in the tank after a fill up?
Filling the tank with compressed air would not return the tank to its original shape and it would be dangerous to try.
Last edited by onehundred80; 08-16-2009 at 08:47 AM.