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2007 Outback Limited
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My fuel gauge on my 07 Limited refuses to go above a 1/4 tank. Once in a while to tease me it may almost hit 1/2. I have tried the techron ten the seafoam a number of times and i know the next step is checking the resistance. The question is since the gauge does not go above a quarter the digital readout never goes above 100 miles to go and the gauge and readout then finally start to drop normally once it reaches that point. So this means my problem is limited to the sensor that reads the top part of the tank right? Would that be the one with the fuel pump or the other one?

After doing the head gasket, timing belt, struts, tires, brakes and who knows what else - this is the last quirky thing to fix (for now) to bring her back to nearly feeling new.
 

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There's two sensors, but they aren't set up to read "the top [or bottom] part of the tank". Rather, they read the level in the right and left side of the tank.

The tank straddles the rear drive shaft, sort of like saddle-bags, so it has two large areas on either side with a part that bridges between the two. One sensor is in the right side tank where the pump is located, the other is in the left side tank. The two sensors are connected in series, so it's the combined resistance of the two that determines the gauge indication.

When the combined resistance of the two sensors (they're wired in series) is low (<10 Ohms) the gauge should show full. When combined resistance is high (~95 Ohms) the gauge should be at empty. If the gauge does not go above 1/4, then that suggests the combined resistance is staying high. That could be a faulty sensor or a bad connection, Without measurements there's no way to tell.

The main sensor resistance (right side, with the pump) ranges from about 3 Ohms to around 31 Ohms. The sub-sensor (left side) ranges from near 3 Ohms to approximately 61 Ohms.

If the tank is full when measurements are made at the sensor connectors, then the resistances should be low. If they are, then there could be a bad connection in the wiring between the sensors and the Body Integrated Unit.

Interesting symptom. Hope you'll keep us informed.
 
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