So my gas guage only works if more than half a tank of gas is in the tank, if the needle goes below the half tank mark it quickly drops to empty and the light goes on. I use the trip meter and MPG computer to estimate when i need to fill up. The thing is when the gas light is on the cars computer must throttle performance to save on gas because the thing is so sluggish but when I fill it up enough to register on the gauge which also means the gas light is off i get all the performance back. I know i need to replace the float and sender unit but is there a way to adjust the gas guage or trick it into thinking i have a fixed level of gas so I dont have to spend money and tear apart my gas tank.

 

Look here:
How to replace fuel pump Volvo S40 and V40 (1996 to 2004)


Getting to the fuel level sensor is pretty easy, not too much has to come off. And you might get away with simply cleaning the contacts on the sensor (look at the last few pics in the link)


If that doesn't work, AND you really want to be cheap and not replace the level sensor all together... I suppose you could pull the pump/sensor assembly out and wire the float to the highest reading.