This is a 1999 K1500 4.8 liter. This truck was towed in after sitting for over a year. The Fuel Pump was bad, so installed new pump and truck would run but it ran rough. Found corroded wires on Cylinder 1 and 3, installed new wires and plugs, ran better but still running rough. I hooked it to Snap-On scanner and got a Code PO300, misfire. Checked data screen on scanner and got a Cylinder 5 and Cylinder 7 misfire. Performed compression test and cylinders checked Okay. Performed spark test and had spark to 5 and 7 cylinder. I also performed a fuel injection cleaning and it didn’t change 5 and 7 misfire. Any ideas what I should try next?
Monday, January 2nd, 2012 AT 11:32 PM