I am concerned that maybe my old MY94 XJ6 is not properly venting the tank. After reading through various posts on this subject I have understood that a small amount of positive pressure is normal (2psi) but I am concerned that I might have a problem with negative pressure in the tank.

I would like to put some sort of pressure gauge into the system to check to see if it is indeed a slight positive pressure (probably OK) versus a possible large amount of negative pressure (bad result).

Can anyone suggest where I might be able to hook up a pressure gauge in the system? Or perhaps another way to make sure which type of pressure I am getting in the tank?

 

Hi, to the left side of tank there is valve one direction this is this valve who have problem

 

Is it possible in pulling the gas tank out to replace the fuel pump that I might have somehow damaged this valve?
When I have to pull the tank to replace the pump I don't fully remove the tank. I just pull it out on the opposite end from the filler neck far enough to reach the top access port.
Then I let it hang there while I remove the access port to reach in to get to the pump.

 

Control all hoses that not bendiing.