Nissan Repair: Fuel guage sticking, nissan 350z, shuttle valve

Question
The fuel guage on my nissan 350z (early 2003 model) works but is 'sticky' i.e. when i fill the the tank it shows just over 5/6 full and at empty it still shows 1/6 full.  Also between these extremes it jumps around, rather than moving smoothly.

FYI I imported the car from Japan and have been told that when the fuel tank sits empty for a long period it can cause this type of effect?

One further question: the car is quite clunky, especially when braking / accelerating at low speed - a friend commented that it might be the brake calipers sticking?

Thanks,
Steve

Answer
Steve,

I had the gas tank on my 350Z replaced due to this problem.  There is a shuttle valve since the tank is in two parts.  Really, it is one tank but there are two sections joined by the top part of the tank.  That way the tank clears the driveshaft.  The pump is behind the right side and the sender is on the left side.  There is a shuttle valve that does not allow the fuel to transfer properly and you get this wacky reading and that is due tot he shuttle valve sticking and not allowing the fuel to transfer to the other side where the sender is.  If you fill it up early in the morning when it is cold out and when the car is cold it helps to get the car full.  If this does not work start looking for a gas tank.