[TurboTC]

When comparing several fuel pump assemblies, I noticed that the wiring to the main connector (on the hanger) is sometimes backwards. Since the wiring harness on the car should be right, why do some have (+) and (-) reversed on the hanger? Even if (+) and (-) are incorrect on the hanger, they still connect to (+) and (-) on the pump itself.

Could some pump manufacturers actually have the flow in the opposite direction so the pump itself needs wired backwards (at the main connector) to flow correctly? I originally thought it was reasonable to assume if +12V is connected to (+) that fuel will flow out the outlet. I can't see otherwise see why such an obvious mistake would be made by Bosch for instance. See picture.

 

[4 L-bodies]

You are correct, It needs to be wired correctly for pump to operate in correct direction. I have never been a fan of Bosch anything. IMO, this is just another example of why I stay clear of anything with a Bosch name on it. On the other hand, lots of aftermarket electrical parts are very poorly manufactured IMO, not just Bosch.
If you bought the Bosch, you could always try hooking it up "as wired" into a 5 gallon bucket and confirm that it won't work as manufactured. Good for you that you noticed this before installing.