2007 Yukon 6.2 stalls/won’t start when hot

[Campie]

Thanks! I’ll snap some pix later and share. We love the car but as with any used vehicle there are always things that need attention!

 

[Doubeleive]

Thanks! I’ll snap some pix later and share. We love the car but as with any used vehicle there are always things that need attention!

depending on your year they changed the maf design from a screened unit to just a module that mounts in the intake housing in a rectangular slot with 2 bolts.
should be extremely easy to tell the difference. anything after 2008/2009 is just a rectangular module, being it is a 6.2l it may already have the rectangular design but can't say for sure,
pictures would tell a lot.....
looks like there is also option to have a screen or no screen and has a maf module that just clips in with a o ring seal
***this is why you stay away from new design years lol

 

[rdezs]

Also, the Napa Gold filters are made by wix for them.

 

[rdezs]

And I'm thinking your model year has the old style PCV in the driver side valve cover. If so, there's an updated design that's worth getting. Someone will chime in on that I hope.... I can't remember what year they made the change

 

[Fless]

Next time it's a crank-no-start after a hot soak, try using the "clear flood" method. Push and hold the accelerator all the way to the floor, and that shuts off the injectors. While doing that, if it starts after a short crank, an injector is leaking or the purge solenoid (as described by @rdezs) is staying open, or something else is causing excess fuel in the intake.

For test purposes the purge solenoid should be closed (no air getting through it) with no voltage applied -- in the raw -- but open with 12v applied. Polarity doesn't matter for testing.

 

[solli5pack]

Before firing parts at it I would recommend learning how to use the scanner and figure out exactly what's causing the no start condition..installing unnecessary parts could actually bury the real problem even deeper making it more difficult to find...I would start with a purge & seal test on the evap system....

 

[rdezs]

While I concur not to blindly shoot the parts canon at it.....

..... I think that concept needs to be weighed versus this being a higher mileage used vehicle that was just obtained. With that noted, while waiting for a bidirectional scanner to arrive.... I would encourage replacing inexpensive items that are known issues with new. I'm talking spark plugs, wires, mass air flow sensor, map sensor, transmission filter change, serpentine belt, inspect the hoses and make a decision.... Personally on any used car I buy, I always replace the O2 sensors as well. Depending on the mileage and the appearance of the water pump, I often do that as well. And prior to the bi-directional scanner arriving, I would clean and reattach all grounds and check the battery condition and cables. (If the battery cables appear original, we all know that's high on a list for replacement)

These are just basic wear items that one could consider in a complete tune-up per se. It also gives one a good starting point to dig deeper with the bidirectional scanner. I see the parts canon as a problem when you're investing a couple hours, and a bunch of money just blindly going in deep without diagnosing. (Lifters, oil pump, injectors for example)

Some items are worth doing based on the mileage..... Preventative maintenance of sorts. If you do your own work, the oil pick up tube o-ring falls into that category.

The overall condition of the vehicle and what, if any, maintenance records should play a part in the overall plan of attack.

Lol, this is just my two cents on how I approach a high mileage used vehicle. I'm sure everyone has a different approach? For me, I won't let my wife drive off in a new to us used vehicle until I'm 99.9% positive she will not get stranded. (She likes to brag that in 39 years she's never been broke down on the side of the road. So she doesn't question my preventive maintenance methodology)

 

[91RS]

Check that your coolant temperature sensor isn’t damaged. If it is reading a lot higher than the engine actually is, it will cause this. It is very easy to damage and often damaged changing the #1 spark plug.

 

[2 liter beater]

I would probably change your crank sensor. Unfortunately, it’s behind the starter. My new NAPA one came with a lousy o ring that leaked so I did it twice. That exact thing happened to my wife after drive home for 10hrs in triple digits. The starter also failed which didn’t help. Changed both and haven’t had the problem in a year so far. Getting ready for a long road trip this summer so we will seee what happens. Good luck with the troubleshooting.

 

[swathdiver]

This is a very common issue with 2007 6.2s. I don't know what's physically different between them and later years, don't think there is any. However, several people have seemingly solved the issue by wrapping the fuel line to keep it from getting too hot for vapor-lock.

My memory is not so good, the answers are 4-8 years back on the pages of this forum.

 

[dkad260]

Check your brake booster for any leaks. If you have Torque or similiar, what does the vacuum show at idle and when the brake pedal is pressed?

 

[rdezs]

Check your brake booster for any leaks. If you have Torque or similiar, what does the vacuum show at idle and when the brake pedal is pressed?

I've seen more than a couple brake boosters over the years that only leak once the brake pedal is pushed.... Would definitely cause stalling when coming to a stop...

Vacuum testing the booster will tell you for sure.

 

[Campie]

depending on your year they changed the maf design from a screened unit to just a module that mounts in the intake housing in a rectangular slot with 2 bolts.
should be extremely easy to tell the difference. anything after 2008/2009 is just a rectangular module, being it is a 6.2l it may already have the rectangular design but can't say for sure,
pictures would tell a lot.....
looks like there is also option to have a screen or no screen and has a maf module that just clips in with a o ring seal
***this is why you stay away from new design years lol

Hi, thanks for the details. Ours is the traditional MAF, not the rectangular model and it does not have a screen, although it is labeled AC Delco. Pretty sure it’s never been replaced and there was a huge difference in the fuel consumption when I sprayed it with the cleaner so guessing I’ll replace it and mark that off the list!

 

[Campie]

Check your brake booster for any leaks. If you have Torque or similiar, what does the vacuum show at idle and when the brake pedal is pressed?

Sorry, you are way past my limited knowledge of mechanics. The carpool is great and we have had no problems at all except the two times. Both times it was low 90s, we were on the highway, down to a quarter tank and pulled off on an exit to get gas. The car stuttered at the traffic light at the exit ramp, but didn’t stall until we slowed down to turn into the gas station. Both times, after 10 or 15 minutes, it started back up again and was fine. Not sure if there were any codes thrown. I have a scanner, but I am not sure how to use it yet. I’ll get you an update! Thanks!

 

[Campie]

I've seen more than a couple brake boosters over the years that only leak once the brake pedal is pushed.... Would definitely cause stalling when coming to a stop...

Vacuum testing the booster will tell you

Check your brake booster for any leaks. If you have Torque or similiar, what does the vacuum show at idle and when the brake pedal is pressed?

not sure I can figure out how to do that, but I will think on it and see what I can come up with!

 

[Campie]

This is a very common issue with 2007 6.2s. I don't know what's physically different between them and later years, don't think there is any. However, several people have seemingly solved the issue by wrapping the fuel line to keep it from getting too hot for vapor-lock.

My memory is not so good, the answers are 4-8 years back on the pages of this forum.

Yes, I have certainly seen that suggested and would be happy to give that a try. Unfortunately, I’m at a loss as to how to do that. I know what the fuel rail is, and I’m guessing the part that needs wrapped is behind the engine where it goes down And passed the transmission. Correct?

 

[Campie]

@Campie I can't think of anything that would cause it to not start once it's hot but when I experienced cranking without ignition was after a rebuild, I didn't have the negative battery cable tightened all the way down to the front of the passenger side head. After I tightened that it fired right up.

Yes, we had that problem also. A part of the clamp on the negative was missing. Once we fix that, it was good! This stalling/no start is different though.

 

[Campie]

Sounds to me like your vapor Purge solenoid. It literally takes just a couple minutes to change it. If it's stuck open, it's getting flooded with fuel vapors from the carbon canister. Pretty common issue.

Below is a picture of it and the part number. You'll see it on the driver side of your intake manifold alongside the fuel rail.

View attachment 459865

OK, i have the part and I have located the old one in the vehicle, but I can’t figure out how to get it off of the metal clip. Can you help?

 

[Campie]

Next time it's a crank-no-start after a hot soak, try using the "clear flood" method. Push and hold the accelerator all the way to the floor, and that shuts off the injectors. While doing that, if it starts after a short crank, an injector is leaking or the purge solenoid (as described by @rdezs) is staying open, or something else is causing excess fuel in the intake.

For test purposes the purge solenoid should be closed (no air getting through it) with no voltage applied -- in the raw -- but open with 12v applied. Polarity doesn't matter for testing.

Actually, we did try holding the gas pedal down and that didn’t fix it. The only thing that fixed it was 10 or 15 minutes with short cranking every 3 to 5 minutes.

 

[Campie]

OK, i have the part and I have located the old one in the vehicle, but I can’t figure out how to get it off of the metal clip. Can you help?

Never mind, got it! Unfortunately, we won’t know whether it works until we are pulling the camper and it’s 90° and we need to get gas. But at least I know it’s done now, thanks!