Cold weather trouble starting. What could be wrong?

[Mfr105]

I have a 2015 sierra 1500 4.3 z71 with 14,000 miles on it. I took over my brother lease from the east coast (no winter package). When below 15 degrees or so it has a really hard time starting. Battery is strong. Cranks over up to 8 times powerfully before it catches at all. I have run isoheet through the tank and lines. What else could the the issue on such a new truck?

[Heavy 5.7]

Any codes? 15° ain't cold at all...

[scott19677]

These DI engines do take longer in cold weather to crank over. Especially if you run on E85. There may not be anything wrong with it at all. There is section on crank times on the owners manual with times @ what temp. One thing you might try is to turn the key to get the fuel pump primed for a few seconds before starting.

[silveradosid]

do like scott19677 says it does help to wait a few second before cranking