Ok so i spun a rod bearing in my 97 yukon gt after looking at all my options I ended up buying a used tbi with a recent a c Delco engine rebuild (proven). only it blew a head gasket. tore both engines down leaving crank rods pistons and nothing else and transfered all my vortec parts to the tbi block except for the roller cam. I installed a cam from a trusted friend who said it would work with my computer as I'm aware they're sensitive to cam upgrades. it was a ft cam with shark tooth heads, same intake, upper and lower. truck fired and idle with an extremely hard cam lope and soon as you touch the throttle it looses all vacuum and fuel. It just won't run, i went back to the stock roller set up. everything back hooked up, dist. Stabbed right on tdc 1 on compression.then adjusted valves at tdc#1 compression then on tdc #6 remaining valves adjusted. all buttoned up try it and just cranks won't start .60 psi fuel pressure, no spark at plug, went back to coil nothing out, 12v into the coil, so I thought coil. changed coil and module beside it and same thing no fire. all ecm fuses etc good, crank sensor and wiring good, all ground good I'm loosing my mind as this is my only vehicle any help greatly appreciated

 

I tried really hard to follow this but I found one period and I think it was for an abbreviation. Are you saying it ran bad with the replacement cam but when you went back to the stock cam, it wouldn't start? I don't think they had a mega fuse in these until 98. Blown fusible link maybe but I think that would only effect the starter?

 

Sorry about that. I edited it so it should be more comprehendable now. and yes I believe you are correct. starting charging circuit is the only one that should be affected by fusible link

 

And yes it ran poorly with larger cam. But running period verified that prior to going back to my stock cam it was firing. Not sure what I could have done during cam swap to cause this no spark issue

 

I'd would be looking for that one connector that is loose or forgotten. Been there, done that, grrrr.

 

Ok I figured it out the crank sensor I replaced was also bad. so she's alive now and running much stronger than before