Crank no start after rebuild?

2004 CHEVROLET SILVERADO
220,000 MILES • 5.3L • V8 • 4WD • AUTOMATIC
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DALTONTROTTER
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  • 9 POSTS
Recently rebuilt my whole top end in my 5.3 and threw a cam”mad max” in it. I replaced every sensor on the engine with ac delco. I installed an after market intake called aces efi. The truck is getting fuel and it’s getting spark. I don’t have a fuel return line I just plugged it but I don’t think it should affect it that much. When cranking everyone once in a while I’ll get some fire out of the exhaust which is just long tube headers no full exhaust yet. Any ideas on what’s wrong with it?
Nov 29, 2025 at 11:02 AM
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DALTONTROTTER
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  • 9 POSTS
Truck will shoot some flames when cranking but just won’t start.
Nov 30, 2025 at 10:57 AM
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DALTONTROTTER
  • MEMBER
  • 9 POSTS
I changed out my crank and camshaft sensor with my old ones which still worked and that didn’t fix the problem all of the grounds are good too
Nov 30, 2025 at 11:00 AM
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STRAILER
  • ✓Experienced Mechanic
  • 55,065 POSTS
So with this camshaft it can be holding the valves open, I would remove the spark plugs and do a compression test to make sure this is the problem. Here is a video to help you.

https://www.youtube.com/watch?v=KOxIm1F8AW0

Get back to me with the readings please.
Dec 1, 2025 at 2:11 AM
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