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My '07 Z06 recently began throwing P2066 codes, along with a failing fuel gauge and fuel system errors in the DIC. The car has only ever run Chevron (Techron). I dropped the passenger fuel tank to access the fuel sending unit. I don't see any evidence of deposits, but not really sure what the deposits would look like anyway. The burn marks at the solder joints are really suspicious. Anyone else encounter those burn/scorch marks? I'm not really sure why this sending unit failed, so I don't have much confidence that just replacing it will be a long term solution
You can measure the resistance of the sending unit...you will see high resistance when the tank is full and low when empty....full is around 225 ohms and empty is roughly 64 ohms.
Usually high resistance like a poor connection will cause that…there is a 5 volt reference voltage that gets pulled to ground through the position of the wiper so it’s not like there is high current flow there and it is a simple potentiometer.
Chances are, it not the stat board that has the problem so much (is grooved from swiper and may be half the problem), but the swipers on the arm worn out instead.
If swipers are gone (and with board bars grooved), then just pick up another sending unit, de-solder the sending unit from the pump, and solder in the new unit.
Also, make sure your getting the correct year sending unit, since the reversed the ohm reading off the unit in the later C6 years.
If you do have the wrong unit and it reading backwards, then can use HP tuner to reverse it in the ECM, but hell of lot cheaper to just get the correct sending unit, over the cost of getting/using H tuner on the car.
An on solder joints, looks like someone already replaced the sender at some point (or bottom wire broke free from board), since bottom solder joint looks like someone was using a soldering iron with too much heat.
The solder joints look to me like they used flux with the solder, which left a bunch of flux ( golden, brown) residue on the circuit board. After soldering, the flux should be removed with a solvent, otherwise if it gets on the contacts, it will hinder a good contact between the contacts and the wipers.
Yes, I think it was around 2007 they Reversed the ohm scale for the sending unit so be careful you are in that zone. Measure what you have now and make sure it matches what you get.
Fuel sending unit assessment
