Dying on idle.

[2007 Denali XL]

Here is the hot soak fuel pressure test. On my test drive the pressure gauge needle was very steady on the drive out, but after stopping for 20 mins, on the return journey the needle flickered a lot like you see here in the hot soak.

 

[Doubeleive]

what happens with the fuel pressure when/as-it dies?

 

[OR VietVet]

what happens with the fuel pressure when/as-it dies?

Exactly. That is the key. If it stays fine, then move on to a different diagnosis.

 

[2007 Denali XL]

what happens with the fuel pressure when/as-it dies?

the dying symptom is not consistent, it kinda only comes along after heavy hot drive. Should be able to recreate that over the next few days

 

[dubyagee01]

If I remember correctly theres a check calve in the fuel system that keeps the lines full. If its bad the lines drain out and it gets hard to start or the fuel lines may have been moved with the trans work and they are near a hot spot and the fuel is boiling in the line.

 

[PNWYukon]

The fuel pressure should be steady and not bounce around at all. You should really find/buy/rent a good scan tool and monitor the live data/mode 6 data like your fuel trims, misfires, injector pressures, etc., to really see what is happening. Otherwise you may just keep chasing in circles.

 

[2007 Denali XL]

If I remember correctly theres a check calve in the fuel system that keeps the lines full. If its bad the lines drain out and it gets hard to start or the fuel lines may have been moved with the trans work and they are near a hot spot and the fuel is boiling in the line.

do you know where that valve is?

 

[dubyagee01]

do you know where that valve is?

Usually in the fuel pump assembly.

 

[2007 Denali XL]

So after 2 weeks of attempting to recreate the dying on idle issue I am giving up. I done same drive 4 or 5 times now where it occurred and apart from some very minor instability in the idle it has not failed once since my last post.

All I can think was that as it has been sitting for 4 months prior to having the trans replace something got bunged up somewhere and it has now cleared itself. I will have the fuel pump replaced at the next service just for safety sake.

Thanks for everyones feedback and help, it's much appreciated. If I ever get to the bottom of it then I will be sure to post it.

 

[OR VietVet]

I do hope it is ok now and not going to give you problems. Please do tell us if you find more info later that points to the original problem because that info is shared and used by all members here. I always like that I can pin point the exact problem and replace a part and know that I can drive my rig with confidence. In this case that may gnaw at you, I hope not though.

 

[wjburken]

I do hope it is ok now and not going to give you problems. Please do tell us if you find more info later that points to the original problem because that info is shared and used by all members here. I always like that I can pin point the exact problem and replace a part and know that I can drive my rig with confidence. In this case that may gnaw at you, I hope not though.

I am very leery of problems that “just go away”.

 

[2007 Denali XL]

IT’s BACK........

After a while of solid driving with no issues my Yukon died again yesterday in a similar way to before.

Been driving around the mountains, filled him us with gas, drove on highway for 20mins, exited freeway and then died and no restart, lots of cranking but no start. Left him on the side of the road for 2hrs, returned and started first time!!!!!!

Interestingly, I have been freewheeling down the mountain recently and when I do this the fuel gauge drops to zero......I have to think this is connected to the same issue.

Should I start with changing the fuel filter (I can do that)or just go ahead and replace the fuel pump unless anyone has other suggestions?

BTW, any suggestions on what I should be paying for the pump job to be done? I would attempt myself but I have no way of getting the car up to access the tank

 

[2007 Denali XL]

y

I am very leery of problems that “just go away”.

your were right...........!!!!!!!!

 

[OR VietVet]

At this point it would be less expensive, in the long run, to sell the rig and get a dependable NBS........just kidding but I hate intermittent problems. The newer the rig the more I seem to see them on 2007 and newer.

 

[OR VietVet]

IT’s BACK........

After a while of solid driving with no issues my Yukon died again yesterday in a similar way to before.

Been driving around the mountains, filled him us with gas, drove on highway for 20mins, exited freeway and then died and no restart, lots of cranking but no start. Left him on the side of the road for 2hrs, returned and started first time!!!!!!

Interestingly, I have been freewheeling down the mountain recently and when I do this the fuel gauge drops to zero......I have to think this is connected to the same issue.

Going to replace the fuel pump unless anyone has other suggestions?

BTW, any suggestions on what I should be paying for that job to be done? I would attempt myself but I have no way of getting the car up to access the tank

The price would depend on the shop that fixes it. I am now assuming you don't already have a shop you take your rig to. The dealer will be expensive, with a capital "E". I have an independent shop that I personally know the 2 techs and they let me supply my own parts. This is if I don't do the job myself.

 

[Tonyrodz]

I def would swap the fuel pump. If the pump is on its way out they always seem to go out once you fill it up.

 

[PNWYukon]

You have got to get this rig hooked up to a live data scan tool!

 

[2007 Denali XL]

N

At this point it would be less expensive, in the long run, to sell the rig and get a dependable NBS........just kidding but I hate intermittent problems. The newer the rig the more I seem to see them on 2007 and newer.

NBS?

 

[2007 Denali XL]

The price would depend on the shop that fixes it. I am now assuming you don't already have a shop you take your rig to. The dealer will be expensive, with a capital "E". I have an independent shop that I personally know the 2 techs and they let me supply my own parts. This is if I don't do the job myself.

I do have a pretty good Tech to take it to, they have done most of the minor work in the past

 

[OR VietVet]

NBS is 2000 to 2006. Yours is NNBS=New New Body Style=2007 to 2014.