P00C6 code, Low Fuel Rail Pressure

[Lazorith James Vaughn]

Ok, so I got the engine back together and started the engine. The engine turned over instantly. ran for a good 30 seconds to a minute.. before suddenly sounding like an exhaust leak happened. It ran rough. I quickly turned it off. Ever since then, sometimes it would start, but would run rough. Otherwise, just cranks, stumbles, acts like it wants fuel.

I'm wondering is this could be due to bad timing. I won't rule it out since it was working prior to be taking it apart.. but as stated.. it was running well!
* I did reuse the Actuator Valve Bolt... Could reusing this bolt cause this issue?
* The ONLY code I had is the P00C6 code for Low Fuel Rail Pressure.
* Research says this code is related to that damn bolt. (But primarily points towards the High Pressure Fuel Pump.)
*Research says that High Fuel Pressure Pump is located on top of the lower intake manifold, below the upper intake manifold. I'm really like to know how to verify absolutely 100% that that's the culprit.

Edited December 25, 2018 by Lazorith James Vaughn
additional info

[silveradosid]

maybe this will help you https://gm.oemdtc.com/3323/engine-runs-with-intermittent-crank-no-start-with-p0011-or-p00c6-2014-2015-chevrolet-gmc

[Lazorith James Vaughn]

Thanks for the reply. I finally determined the issue here. The issue was fouled spark plugs from turning the engine on and offer with 3 to 10 second intervals.

I was going to blame poor timing set. Negating all my knowledge that I know I set everything properly. But, ah well. what's done is done. Truck runs again!
Though, the HpFp may be weakened now due to extended crank times