My gauge only reads half full when I've completely filled the tank. It fall as if normal until showing empty. It will then hold only 6 to 9 gallons. Can my tank be limiting it's capacity or do I have a faulty gauge?

 

Most likely fuel level sending unit in tank.

 

What year is the car?

 

It's a 2001 V70XC

 

The 2001 and newer cars have 2 sending units for the gauge. The tank is a saddle tank like setup. There is one sending unit on each side. Then the computer averages both of them and sends a signal to the gauge on the dash. So one of them is bad. Now the bad part is you need to find someone that has a scanner that can read both sending units so you can figure out which one is bad. One is an easy swap. The other one is the entire fuel pump and sending unit in one.

 

Plan B: treat it as if it were a motorcycle, most of which have no fuel gauge at all. The trip odometer becomes your fuel gauge. Learn how far the car will go on a full tank, (given at least 20 miles "reserve", of course) and reset the trip meter with each fill up. Motorcycles do, however, have a "reserve" setting on the tank petcock which you have to flip to get those last miles out of the tank. Your Volvo does not.

Does the "low fuel" light still function correctly? That's your "reserve" petcock -- time to fill up.

This plan, of course, depends on YOU being the regular driver and learning how much it will cost to truly fix the fuel gauge problem.

 

I have a similar problem in the fuel gage of my 2006 XC90 V8: the fuel gage shows full tank when I fill it up but the gage does not go below half a tank full after driving and consuming the fuel. The first time it happened I ran out of gas and the gage showed half a tank full left. Next time I filled the tank it worked fine but now the problem has come back. Does anyone have the part number for the two senders?

 

https://www.tascaparts.com/auto-part...omponents-scat

 

Thank you.