2018 Sierra 6.2 tough starting

[Boyd Proctor]

Hey guys,

I have a 2018 Sierra A/T w/ the 6.2, 75000km. I was using a Range AFM disabler but recently stopped. It seems like my truck struggles on cold starts – it takes 4-5 cranks before it will fire up. I replaced the battery as I thought this was this issue but I didn’t help. Cold starts are legit cold starts as in sat outside in -20° C for 12+ hours, it always is plugged in. I’ve also tried to turn the key to on and let the fuel pump prime the fuel system. Once it starts then it’s fine to fire up right away once the key is turned on. Note I was running 87 octane but switched back to 91 octane 2 tanks ago due to the issues.

Is this common for the direct injection engines? It seems like a fuel pressure regulator isn’t properly working but these trucks only have a pressure sensor in the tank?

Any help is appreciated.

[silveradosid]

my 2014 5.3 is the same as yours

[M1ck3y]

I've experienced something similar. My truck starts better when it hasn't been plugged in; still do when -18 or lower. I don't know the reason for this, but I haven't noticed anything else indicating a problem.

[BlaineBug]

I've never had this issue but I notice that when the weather is COLD and I'm also using E85 that the cranking is longer than usual.  But maybe by 1 second or so.

[M1ck3y]

6 hours ago, BlaineBug said:

I've never had this issue but I notice that when the weather is COLD and I'm also using E85 that the cranking is longer than usual.  But maybe by 1 second or so.

 

Yeah, ethanol doesn't like the cold. 

[Chris Manchur]

I know exactly what you're talking about, have had the same thing happen on my 2015 6.2L. I'm used to the 2009 Sierra starting up much quicker, so I took a look online and found this service bulletin from a few years ago. 

 

https://static.nhtsa.gov/odi/tsbs/2018/MC-10137203-9999.pdf

 

Apparently the fuel pressure needs to build up which is why it cranks longer than normal, and so far I've started mine in -25 C weather both plugged in and not and it didn't seem to matter.

 

The bulleting mentions it could take up to 5 seconds to start in those temps, and if you count it out that's a long time! However I've always had mine start sooner.