i have a 2000 silverado with the 5.3 and i was wondering when the truck is running you can hear the fuel pump running but when you go to start the truck you cant hear it come on and sometimes i have to crank on it for a while(5-10 sec) to get it to start. it runs vey well. if it sits over night it starts very easy, if you shut it off and restart it starts easy but if you let it sit an hour then its hard to start. what do you thin kcould be wrong? it has new plugs, fuel filter, and top end fuel injector cleaner..