1999 5.7L 2WD Suburban has 180K miles. Runs great. never misfired. I use Techron every 5-7k miles to clean injectors and fuel system. Started with no problems. Then it took two cranks to get it to start. 2 weeks later my wife started it, drove it. went to restart. Car cranks, not starting. Towed to dealer. They want to replace fuel pump ($910). took it out of there to a repair shop. They said they checked filter (clear), Schraeder valve had 45psi from pump. 2nd mechanic says its the spider set of injector lines which need replacement.= ($980). These two stories don't add up. Anybody ever experience this system. Is it something simple. The relays are good. No blown fuses. Thanks. Dave