It depends if the pump is weak or quits pumping entirely. If pump quits entirely the engine will quit and not restart. If pump is weak on volume the truck will lack power. I have had several trucks have the lift pump be weak and no damage to the CP3 pump and have over 300,000 miles on. Have also had several trucks quit due to pump failure and not damage the CP3 pump and are still going strong at 300,000 plus. These were the fuel filter mounted pumps that came on them originally. The new revised intank pump I have not seen any failures on yet, Have a couple of 2005's with over 150,000 and no failures yet.