Fuel Gauge problem

[Dous]

Hey so today my fuel gauge decided to crap out on me, I know there are some sending unit issues that are common in 4runners, but I think that might not be the case with mine. When i first turn on the car the gauge shows full then in a couple seconds in go down to completely empty. So yesterday I was working on installing and amp and a linoutput converter. So I took of the left rear door panel and was working in there. Does the line for the sending unit or anything pass through there that I could have messed up? I am just trying to figure this out.

Thanks