It's possible, but highly unlikely. It would have to be completely plugged which would result in absolutely no fuel pressure. That would mean that you would've had stalling problems way before your relay stated heating up. I've replaced tons of these pumps on the w163. A few for the exact same issue that you're having. I would replace the pump AND the filter. The fuel pump was a weak point on the early 163s. If you wanted to be 100% sure that it's the pump before spending any money, you would need to measure the amp draw off the pump. That would be a little difficult since the pump has a plug instead of wiring that you can bypass.