2003 GMC Yukon • 200,000 miles

5.3 flex Cranks, won't start.

Verified all fuses under hood and dash that I know of are good.
Have fuel pressure to the rails.
Have power to the injectors.
Have power to the coil packs.
Don't have spark at the plugs.

I created the issue while cleaning the throttle body with sea foam. It was running rough as expected while spraying. Then died during the process and would not start.
January 27, 2013.

Possible Fouled plugs

Jan 28, 2013.
Good question, plugs are good. I check them and not even wet, which I expected.

Thank you for the help!

Question, I understand that the crank shaft position sensor controls timing and spark. Could that be my issue with no spark? If so, why the heck would it have expired while cleaning my TB?

Jan 28, 2013.
It's running.

Last thing I did last night was remove the crankshaft position sensor.

I reinstalled it this morning, connected the battery and viola started.

Just a recap.
I was cleaning the TB with Sea Foam and the engine stalled and would crank but not start.

No spark
Had power to coil packs.
Had power to injectors.
Had fuel to pressure rails.
Battery disconnected overnight for two nights.

I have no idea why it is running and that is spooky.

Please let me know if you have any ideas.

Jan 28, 2013.