Originally Posted by
EuropeanAM
Follow that harness, and disconnect all of the sensors and connections (note that this would likely include the fuel level sensor). Make sure voltage returns to 5V on that circuit.
If NOT, disconnect that HARNESS from the engine and recheck. Hopefully you're back at 5V on that power circuit.
Re-introduce the harness, then each circuit or sensor, until you can determine which shorted item is the problem.
DON'T assume the first one is the only one. I've found THREE (3) shorted sensors in the same circuit before.