Hello everyone im new to this forum. I have an 04 gmc lb7 which i bought new it has 260,000 on it. New bosch injectors around 20,000 miles ago. Truck was running fine up till about 3 weeks ago i drove it to work no problem went to start to leave and it turned over really slow . Turned ignition off tried again started right up. No issues for 2 weeks parked it at my house it sat for a couple of days and now it wont start at all. I have serious amount of air in system replaced fuel filter housing new filter new wit sensor. No visible fuel leaks. No fuel in oil. I ran fuel line directly into filter housing from fuel can to eliminate everything back to tank and still getting air and no start. Primer pumps up firm soon as it turns over its soft again. I dont have a scan tool so i guess im asking which way to go now. Thanks for any help.