3.0 Duramax cranks but won’t start

WontStart · August 16, 2021

Add another one to the list. 2021 Sierra Elevation 3.0 Duramax Happened twice in the first 1,000 miles and disappeared for a couple thousand miles. Now with 5,000 miles on the truck, it’s happened 7 or 8 times. Always starts right up on the second try.. for now.

Edited August 16, 2021 by WontStart
Coherence

moobaru · August 16, 2021

Just had my second long crank no start , first one was at about 230 miles, this one was at 5690 miles. Second one I had run into a store for about 15-20 min like others have reported. But I had done this several times before with no issue.

GJR1212 · August 16, 2021

3 hours ago, WontStart said:

Add another one to the list. 2021 Sierra Elevation 3.0 Duramax Happened twice in the first 1,000 miles and disappeared for a couple thousand miles. Now with 5,000 miles on the truck, it’s happened 7 or 8 times. Always starts right up on the second try.. for now.

Have you or the dealer tightened the four screws that sandwitch the fuse box together? I have tightened mine to the recommended 53 in lb and then a few weeks later they were loose again and I retightened them. I think the plastic pieces are deforming, probably aided by the high heat of the nearby exhaust reactor that gets super hot during regen. So far I only had one event and none since the first time I tightened the fuse box bolts. It would be interesting to see if a truck like yours with multiple events has loose fuse box screws. I'm sure GM emphasizes the tightening of these screws because my fuse box has hand made, check marks by each screw. It is probably a final assembly QC check. They seem to work loose over time. Nearly all circuits dealing with the engine controls involve this fuse box.

moobaru · August 16, 2021

1 minute ago, GJR1212 said:

Have you or the dealer tightened the four screws that sandwitch the fuse box together? I have tightened mine to the recommended 53 in lb and then a few weeks later they were loose again and I retightened them. I think the plastic pieces are deforming, probably aided by the high heat of the nearby exhaust reactor that gets super hot during regen. So far I only had one event and none since the first time I tightened the fuse box bolts. It would be interesting to see if a truck like yours with multiple events has loose fuse box screws. I'm sure GM emphasizes the tightening of these screws because my fuse box has hand made, check marks by each screw. It is probably a final assembly QC check. They seem to work loose over time. Nearly all circuits dealing with the engine controls involve this fuse box.

Not trying to answer for them, but I was a big cheerleader for the Fuse box bolts as after mine did it the first time I found mine way out of spec. I too re-torqued them a few weeks ago, they were loose. But after my truck did the crank-no start yesterday when I got home I pulled out the torque wrench and all 4 were still at 53 in-lb.

singlespeed · August 16, 2021

19 minutes ago, moobaru said:

Not trying to answer for them, but I was a big cheerleader for the Fuse box bolts as after mine did it the first time I found mine way out of spec. I too re-torqued them a few weeks ago, they were loose. But after my truck did the crank-no start yesterday when I got home I pulled out the torque wrench and all 4 were still at 53 in-lb.

Bummer

macodi · August 16, 2021

So weird that I had 2004 Colorado that was key start but would do a similar long crank no start. Never failed to start within 15 mins. Was a great home depot beater with 160k mi when I sold it a few yrs ago. GM never had a fix for it. Hope that brightens your day.

WontStart · August 16, 2021

2 hours ago, GJR1212 said:

Have you or the dealer tightened the four screws that sandwitch the fuse box together? I have tightened mine to the recommended 53 in lb and then a few weeks later they were loose again and I retightened them. I think the plastic pieces are deforming, probably aided by the high heat of the nearby exhaust reactor that gets super hot during regen. So far I only had one event and none since the first time I tightened the fuse box bolts. It would be interesting to see if a truck like yours with multiple events has loose fuse box screws. I'm sure GM emphasizes the tightening of these screws because my fuse box has hand made, check marks by each screw. It is probably a final assembly QC check. They seem to work loose over time. Nearly all circuits dealing with the engine controls involve this fuse box.

Yes I’ve checked them a couple times. Never been loose and I still get the extended crank no start. Really hoping it’s something simple and doesn’t require removing the cab from the frame like originally thought.

Edited August 16, 2021 by WontStart

Joe Brooks · August 16, 2021

5th crank no start today. I have tightened the fuse box bolts. Jumped out and checked them and one was no longer torqued correctly. But as others have said I’m not confident on this or the exciter wheel. Finally got video of it though.

GJR1212 · August 16, 2021

4 hours ago, moobaru said:

Not trying to answer for them, but I was a big cheerleader for the Fuse box bolts as after mine did it the first time I found mine way out of spec. I too re-torqued them a few weeks ago, they were loose. But after my truck did the crank-no start yesterday when I got home I pulled out the torque wrench and all 4 were still at 53 in-lb.

Thanks for the comment. Sure seems like GM has had enough time to figure out whats going on. If they would just reprogram the crank cycle to running a maximum of say three or four seconds instead of 20 would be an improvement. I would also like for the auto off/on button function to allow you to either turn on the function or turn it off and then hold that setting until you changed it. I dislike having to turn it off each time you restart the truck. When you have a truck that might not restart at a busy intersection shut itself off, you feel sort of stupid wondering what it will do when you let off the brake.

moobaru · August 16, 2021

12 minutes ago, GJR1212 said:

Thanks for the comment. Sure seems like GM has had enough time to figure out whats going on. If they would just reprogram the crank cycle to running a maximum of say three or four seconds instead of 20 would be an improvement. I would also like for the auto off/on button function to allow you to either turn on the function or turn it off and then hold that setting until you changed it. I dislike having to turn it off each time you restart the truck. When you have a truck that might not restart at a busy intersection shut itself off, you feel sort of stupid wondering what it will do when you let off the brake.

This is my first domestic vehicle I have ever owned. I was debating between this (2021 1500 AT4) or the new Tundra. My boss was raving about how great GMCs are. I decided to take the plunge and got the AT4. Right now I am wishing I had waited for the new Tundra, depending on how long it takes for them to fix this I may or may not trade in my At4 when the new Tundra comes out.

macodi · August 16, 2021

31 minutes ago, moobaru said:

Thanks for the comment. Sure seems like GM has had enough time to figure out whats going on. If they would just reprogram the crank cycle to running a maximum of say three or four seconds instead of 20 would be an improvement. I would also like for the auto off/on button function to allow you to either turn on the function or turn it off and then hold that setting until you changed it. I dislike having to turn it off each time you restart the truck. When you have a truck that might not restart at a busy intersection shut itself off, you feel sort of stupid wondering what it will do when you let off the brake.

2019-2021 Chevrolet Silverado 1500 Autostop Eliminator

No experience with this product, but it is one of several ways to disable the auto stop/start feature. $99

MyFordsNeverBreak · August 16, 2021

1 hour ago, moobaru said:

This is my first domestic vehicle I have ever owned. I was debating between this (2021 1500 AT4) or the new Tundra. My boss was raving about how great GMCs are. I decided to take the plunge and got the AT4. Right now I am wishing I had waited for the new Tundra, depending on how long it takes for them to fix this I may or may not trade in my At4 when the new Tundra comes out.

At least if you trade for the Tundra you'll have a real screen instead of the little baby screen in the GM.

V8Chevy · August 17, 2021

I experienced this for the 1st time last week. 2021 Sierra Denali with ~2,000 miles. Mine started fine early in the morning ~6:00 AM and ran fine on my drive to work. It sat at work all day and did it to me when I was leaving work around 4:00 PM.

Perhaps I missed it, but has anyone actually experienced it during a start stop event?

Trying to brainstorm this a bit, but it seems like the issue would have to be tied to the ECM not giving the OK to feed fuel to the cylinders. I say this because the engine is getting air (no clogged air filter) and it doesn't have an ignition system (no spark plugs) to worry about so it really points to a lack of fuel to start the engine. A sensor or condition must be telling the ECM to not distribute fuel to the injectors for some reason. For example, on my GM gas cars, the engine will not start if I mash the gas pedal to full throttle while trying to start the engine as I do this intentionally to prime my oil pump on the first start after changing the oil and filter. My 3.0 no start issue seemed very similar except that I did not have my foot touching the throttle pedal. It's probably something simple causing it...

Edited August 17, 2021 by V8Chevy

GJR1212 · August 17, 2021

2 hours ago, macodi said:

2019-2021 Chevrolet Silverado 1500 Autostop Eliminator

No experience with this product, but it is one of several ways to disable the auto stop/start feature. $99

Thanks, I will keep that in mind. I would prefer a factory fix to keep clean with warranty service.

fireaxxe · August 17, 2021

Has anyone tried replacing the key fob battery? Maybe an intermittent weak signal or interference. I’ve replaced mine but not too confident this is the issue.