Have had a recent issue with an occasional no start condition in my 2001 Z28. Changed relays, fuel pump only a year old. Car would crank but no start several times then fire up and drive fine. Maybe a slight stumble in the idle. Fuel filter was changed at same time as pump. Decided to change fuel filter and found the old filter has a rattle.... like a marble in a coffee can rattle. Anyone ever had one that rattled like that? I think I'm going to open it up and find out what it is. Almost certain I found what the problem was.