One morning a while back I started my '98 Lumina and I heard/felt a 'booming' come from under the car. It boomed twice or three times and that was it. I shrugged it off. A couple of nights ago, I came home from work and parked on our street (slight downgrade) instead of the driveway, and an hour later when I started it to go somewhere it 'boomed' again, but louder and the floor pan shook. I parked it in the driveway and left it there.
I don't think it was a backfire because it was very muffled. I've never heard one sound that way. My concern is that, about 6 months ago, the fuel pump was replaced with an imported item due to cost (Luminas have an insanely expensive 'fuel module' that goes into the tank). Can there be some kind of arcing going on in the tank causing the booms? If that were the case, can't the whole tank blow up?
Am I thinking too deeply about this? Has anyone had a similar situation? Any ideas appreciated.
Harold