.. Truck has spark.. Will not crank off brake cleaner.. Has compression. Fluid levels in check.. Has not been cranked since Monday, always been a hard starter.. Won't even try now.. Was down due to spark plug tube orings leaking bad making a lot of smoke in the plant.. I replaced plugs and o-rings and cleaned wires now no start... It didn't wanna fire up before the work so I worked on it where it sat..

Cleaned wires with electrical degreaser ( as little as possible and this was yesterday)

I pull plug and there is fire jumping across the gap.. Could it not be hot enough?