ope you all can help a little. I have a 2000 Jetta VR6, 5 speed, 88K miles.

A few weeks ago, I replaced the fuel pump relay because I believed it was failing when the car would get warm on a sunny day. It does indeed quit running after about 20 minutes when ambient temp gets above 75 degrees or so, even with the new relay. Runs perfectly when cool out. Anyway...

In diagnosing, I removed the rear seat to inspect the fuel pump. I noticed that during those times when the car will not start or run, I can still hear the fuel pump. Can the pump be making its normal humming noise and yet still NOT work? Or when it fails, is it simply silent?

Thanks, I appreciate the responses.
Jack