Crank no start after rebuild?

2004 CHEVROLET SILVERADO
220,000 MILES • 5.3L • V8 • 4WD • AUTOMATIC
Avatar
DALTONTROTTER
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 7:02 PM
Advertisement
Avatar
DALTONTROTTER
  • MEMBER
  • 9 POSTS
Truck will shoot some flames when cranking but just won’t start.
Nov 30, 2025 at 6:57 PM
Avatar
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 7:00 PM
Avatar
STRAILER
  • ✓ASE Certified Mechanic
  • 54,494 POSTS
  • ASE Certified Mechanic
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 10:11 AM
Join 2CarPros for free, one of the most advanced car repair communities on the internet. From first-time drivers to seasoned mechanics, everyone is welcome to reply, share details, and get better answers. You can add a temporary image or video first; uploads are limited to 20 MB.
Ask a Free Question
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.