Scotty I have a 99 Chevy 3500 express van with the 5.7l I have spark fuel and air but not firing up what do you think it could be

try this video and if not any of those, often a blown head gasket or flooded out engine from leaking injectors https://www.youtube.com/watch?v=064Ilsz8Fzg

Ok I tried them both I think I’ll have to do a compression check and see if I have a bad head gasket because I can’t see any bubbles in the radiator as it’s sealed all I have is the over flow basket