Is the direction of fuel flow in a 1994 Maxima restricted to flow only from the tank to the engine? In other words, is there some sort of a backflow preventer that keeps fuel in the line from flowing back to the tank when the engine is shut off?

The reason I ask: The local Nissan dealer hooked up a Ford pressure smoke tester to the fuel line under the hood and tried to force smoke back to the fuel tank in order to see if they could detect a fuel leak comming from the tank area. I suspect that it is a corroded fuel filler tube (1996 recall). They saw no smoke comming from the fuel tank area. If there is indeed a backflow preventer, then of course they would not see any smoke because it would not make it back to the tank anyway.

I would appreciate any help on this. Also, have any of you had sinliar experiences with fuel odors comming from the filler tube area?

P.S. I installed a new OEM gas cap just in case the old one was worn out.

 

YES there is a check valve that will prevent back flow of gas, its located near the fuel tank. Most cars have them.

Unless you were talking about the vapor line? but I think you were talking about the fuel line.