How do I repair a non functional fuel gauge on 2001 outback?

Hello, Don Mealey Sport Subaru here to help. We agree with Tom. Subaru calls, what Tom referred to as the Fuel Sending Unit, the Fuel Level Sensor. Please make sure to investigate that when diagnosing the issue with a certified mechanic. You can always bring it in to our shop and have one of our Subaru Master Technicians look at it for you. We are located in Orlando, FL. I hope this helps.

While you're at it you might as well have them check your low fuel light warning, although, I normally recommend that most people refuel at 1/4 tank. Running your fuel down to near empty puts more stress on your fuel pump. You can do if you have to, but, better to avoid that. Still, its desirable to have the low fuel warning light as is an accurate and working fuel gauge. I've personally found the gauge in my 2010 Outback to be extremely accurate and linear. I've had many cars where the needle is just stuck on the full line for a while and then drops off very quickly. I don't like that. Linear is better than logarithmic.