dont even touch take it to the dealer and let them keep it over night and try to start it the next morning so they can fiqure it out and fix it.....

 

Well after googling I found there are alot of people experiencing this on new GM trucks and almost EVERY one was told by the dealer that it is "normal" due to the computer using an overly rich mixture on cold starts. And that none of them were able to get anything done about it since there is no CEL or actual code being thrown from the situation

 

turn the key on . let it sit for 3 seconds, then turn it back off... then turn it back on.... wait 3 seconds.... then try cranking it....

 

This is my first post on the "performance trucks" side. Greetings aside, It sounds like a failing fuel pump to me. It does not sound normal. I just picked up a 2010 2500, and haven't noticed anything like this. If it were me, Id remove the beauty cover on the engine, find the test port on the fuel rail, and check the pressures. key on, engine on, and holding pressure. If the rail loses pressure, the diaphragm in the pump is going.
Oh, and Hi all!
Ben.

 

sounds like some bad gas lol

 

Tested a theory this morning and I think I found out what's going on. If I IMMEDIATELY crank it instead of letting the fuel pump prime up then it's fine. But if I let it prime for a few seconds then it dumps too much fuel in causing the rough idle... Going to try this again tomorrow too make sure I'm right but today it cranked like it's supposed to so I'm thinking I am on the right track

 

I'd just about bet that the anti-drainback check valve in the pump module has failed.

 

I had this problem with my 5.3 Avalanche. I used HP Tuners software to adjust the "cold start" setting for more fuel up until approximately 100' F coolant temperature. This cleared up the problem 90% of the time.

 

At work we have a 09' 2500hd and it idles real ruff for a few seconds on every cold start. It never dies but just rough idling. There is something not quite right here. My 07' idles rough on cold start sometimes also.

 

i've had a similiar problem on my '08 silverado, but only in remote start. the truck is just over 2 years old with just over 36k on it and it's only happened in remote start and only 3-4 times tops. i remoted started the truck and within 1 second from starting it shuts right off, i turn it with the key and it fires right up.