I am in the final stages of my motor swap of a 7.3 idi with hypermax turbo into a 73 Ford Highboy. This is my second 7.3 I've put in, my last had bad head gaskets and as a 16 year old I decided to get another rather than tackling that right now. This motor supposedly was rebuilt recently and should be ready to go. I replaced the glow plugs right away because I had new motorcraft ones on hand. I had the motor coughing to life but now won't fire at all, even if I unhook the glow plugs and try to give it a little nose candy ((either), ik it's not good stuff) but it won't even cough with that. In my experience that should bypass any fuel/air in the fuel issues. Leading me to think the timing was off, I can look on the pump to timing cover and the marks line up, so before I go thru the pain staking task of assuring that the guy who rebuilt it didn't get the pump drive gear a tooth off of the cam, I wanted to see if you guys knew of any other possibilities as to what is going on. I also replaced the leak-prone return line caps and noticed that when I blew back into the return line system there was a ton of resistance, and when I unhooked the return line that goes into the IP fuel sprayed out (it was pressurized). Could a clogged return line cause a no start because of a fuel issue? Just grasping at straws here I am unfortunately lost right now. I was considering replacing the IP with a spare one I have laying around that I know works, but figured I'd ask for help before I do that too. Any help is appreciated!