Why solder the FPR? BECAUSE IT MIGHT BE BAD DUE TO A PROBLEM WITH YOUR FUEL PUMP(S)! The FAQ has simple tests on checking the main and in-tank pumps. This is something I failed to do and you shouldn't.

Here's the full story: I resoldered my FPR several months back and the car was running fine until two days ago. It just quit in heavy stop-and-go traffic. The car just died softly, like it was doing when the FPR first went bad. I thought maybe I hadn't done a very good job with the resoldering and would just buy a new one. I had the car towed to a reliable mechanic who told me that the FRP was fine -- power was being delivered to the main fuel pump, but it was frozen up and wouldn't turn. On further trouble shooting, he also confirmed that the in-tank pump was bad (I have the Bosch fuel system on my '89 740 turbo).

The main fuel pump failed because it was working extra hard trying to make up for the failed in-tank pump. My mechanic speculates that the FPR fried due to the extra current draw required by the main pump. At no time did I ever get an indication that the in-tank pump was bad like I expected to see ... hesitation and possibly dieing when the fuel dropped below 1/2 tank. The car appeared to operate normally at all times. On the positive side, I confirmed that I can solder and I now have two good fuel pumps in my car.