2007 GMC Denali stalls after towing

[puckhead]

Thanks for the info guys. It is just something that is recommended on a diesel forum I go to for reducing exhaust temps, didn't know if it was the same for gas engines.

I did notice that after I got the auxiliary transmission cooler installed that my outside temperature on my rear view mirror reads much higher than normal. I think I found the sensor and might try to move it somewhere further away from the transmission cooler radiator.

 

[tgui]

You'll need to make sure its away from the cooler and in an area where it gets air flow. I had to move mine on my prev Yukon when I did a large trans cooler.

Per the stalling issue, the fuel line runs by the trans and I think pretty close to the drivers exhaust. I'd see if it were possible to wrap it. I wrapped my prev Yukons trans lines with the pictured stuff and it worked well.

 

[puckhead]

Thanks dude! Do you think that could have anything to do with the overheating? Not sure if that sensor has any other function other than outside temp for the rear view mirror.

 

[tgui]

Nah, that sensor doesn't do much at all.

 

[swathdiver]

Yes. This. As someone temporarily living without cats the smell at stoplights can get pretty bad. Its not worth it.

Really? I guess I don't remember anymore. First thing we did back in the day was gut or remove those things. I do remember the smell of VP Race Fuels 117, AVGas, 104 Unleaded but nothing objectionable and certainly not while driving.

The smell of stinky cars made it through my cabin filter today but I knew it was not me as we're running E85 and smells like french fries or maybe corn on the cob!

 

[tgui]

Really? I guess I don't remember anymore. First thing we did back in the day was gut or remove those things. I do remember the smell of VP Race Fuels 117, AVGas, 104 Unleaded but nothing objectionable and certainly not while driving.

The smell of stinky cars made it through my cabin filter today but I knew it was not me as we're running E85 and smells like french fries or maybe corn on the cob!

Maybe I'm just a *****.

All my fast cars/trucks have had at least high-flow cats. Yeah E85 is a totally different beast too. My STi friends would run that. I never did, but probably should have tried it! I was doing 24psi, 15.5 degrees at peak torque on regular 93 so was pretty happy.

 

[swathdiver]

Maybe I'm just a *****.

I doubt that! Maybe you need better filtration, quit cutting your nose hairs so close! LOL

 

[JEFFC]

Any idea what caused the fuel to heat up? Bad wiring?



Any update?

No, not bad wiring. I really do not know if the fuel is any hotter then it ever was before this started occurring. I have owned it since new and the fuel lines have never been repositioned. My mechanic is convinced that our fuels have been reformulated and this is what caused the issue. No other explanation. If you want to determine if this is your problem, get a fuel pressure tester and try the bleed off trick. Nothing to lose. You could also try some ethanol free premium if available. (less tendency to vapor lock)

 

[cdig]

I'm wondering if anyone has ever found a proof positive fix for this issue. To date I have replaced the crankshaft position sensor, wrapped my fuel lines in insulation, tried the gas cap vent, and I still had the same issue. I then took it to my mechanic who diagnosed the problem as camshaft sensor, as it appeared to be out of range... I approved the replacement of the camshaft sensor (to the tune of $700) only to have the same issue. He then suggested that we change the oil, and add some additive. This actually appeared to resolve the issue, as on the next trip out with the boat under the same high temp conditions, the truck did not stall when coming to a stop. Awesome, I thought. However, after a few more weeks we went out on another outing with the camper, and the truck again died on us when coming to a stop. Mechanic says that it's likely the cam phaser gears or something internal... Which is big money to fix. I don't feel like playing a guessing game!

 

[Doubeleive]

I'm wondering if anyone has ever found a proof positive fix for this issue. To date I have replaced the crankshaft position sensor, wrapped my fuel lines in insulation, tried the gas cap vent, and I still had the same issue. I then took it to my mechanic who diagnosed the problem as camshaft sensor, as it appeared to be out of range... I approved the replacement of the camshaft sensor (to the tune of $700) only to have the same issue. He then suggested that we change the oil, and add some additive. This actually appeared to resolve the issue, as on the next trip out with the boat under the same high temp conditions, the truck did not stall when coming to a stop. Awesome, I thought. However, after a few more weeks we went out on another outing with the camper, and the truck again died on us when coming to a stop. Mechanic says that it's likely the cam phaser gears or something internal... Which is big money to fix. I don't feel like playing a guessing game!

have you tried relieving the fuel pressure on the fuel rail when it happens?, if that works then you may still have heat related fuel problems this isn't a very "typical" problem it only seems to crop up for a few people when they have been towing. what are your engine and transmission temps running when towing?

 

[syclnjr]

Finally! I found more than a couple of people that have the same issue Not a good thing really but good to here some things that have been attempted to fix the situation.

For mine 2008 Yukon Denali, 129K miles on it. Only came about on mine after we purchased our travel trailer and went on our first trip. Trailer is around 5500 pounds fully loaded and is 24 foot long, shouldn't have any issues towing it.

As with others after coming to a stop from a about an hour on the highway, it just died, crank and crank and nothing. no check engine lights, no codes etc.

The only thing that I found to get it to start other than waiting is peg the gas pedal on the floor like and old carb car to get it to fire again and after that it would run fine. Or when coming close to a stop, put trans in nuetral and feather the gas so RPMS stayed up.

Engine temp was hovering around 215 ish and trans was about 195 maybe 200 when it first happened.

Everything is near stock on my truck minus the K and N intake and PCM4less tune that I am running. IT runs absolutely fine all the rest of the time.

I am not one to throw parts at any sitaution I like to find the definite answer, but this is just baffling so the list of stuff I am going to do:

• Change the thermostat and the relative fan on times in the tune, going to try a 160 thermostat
• Put in Tru Cool 40K cooler for the trans and ditch the factory cooler.
• I bought silicone wrapped fir proof sleeve for the fuel line, do you guys typically disconnect the fuel line at the rail and with a big enough sleeve just slide it over and down or is there an easier way to do this?
• I may change the oil, but not sure if this will aid in much.

Has anyone found the defnitive answer to this issue that I missed?

I found a conversation on another page where it was recommended to change the THECU in the trans due to a sticking solenoid or control. If I have to dig into the trans I am going to sell this thing lol

Thanks

 

[avalonandl]

I would change the Fuel Pump relay...these can get "tired" cheap about 20$

 

[syclnjr]

I would change the Fuel Pump relay...these can get "tired" cheap about 20$

Thanks good thought , but the pump is running with Key ON when it does this.

Something to add to the list possibly, but with all the people having the issue this hasn't fixed it

Thanks

 

[Doubeleive]

This has been discussed before I thought the general consensus it was it is due to fuel vaporization? when this happens try releasing some fuel at the schrader valve on the intake and see if it starts again without waiting.

 

[avalonandl]

Finally! I found more than a couple of people that have the same issue Not a good thing really but good to here some things that have been attempted to fix the situation.

For mine 2008 Yukon Denali, 129K miles on it. Only came about on mine after we purchased our travel trailer and went on our first trip. Trailer is around 5500 pounds fully loaded and is 24 foot long, shouldn't have any issues towing it.

As with others after coming to a stop from a about an hour on the highway, it just died, crank and crank and nothing. no check engine lights, no codes etc.

The only thing that I found to get it to start other than waiting is peg the gas pedal on the floor like and old carb car to get it to fire again and after that it would run fine. Or when coming close to a stop, put trans in nuetral and feather the gas so RPMS stayed up.

Engine temp was hovering around 215 ish and trans was about 195 maybe 200 when it first happened.

Everything is near stock on my truck minus the K and N intake and PCM4less tune that I am running. IT runs absolutely fine all the rest of the time.

I am not one to throw parts at any sitaution I like to find the definite answer, but this is just baffling so the list of stuff I am going to do:

• Change the thermostat and the relative fan on times in the tune, going to try a 160 thermostat
• Put in Tru Cool 40K cooler for the trans and ditch the factory cooler.
• I bought silicone wrapped fir proof sleeve for the fuel line, do you guys typically disconnect the fuel line at the rail and with a big enough sleeve just slide it over and down or is there an easier way to do this?
• I may change the oil, but not sure if this will aid in much.

Has anyone found the defnitive answer to this issue that I missed?

I found a conversation on another page where it was recommended to change the THECU in the trans due to a sticking solenoid or control. If I have to dig into the trans I am going to sell this thing lol

Thanks

Thanks good thought , but the pump is running with Key ON when it does this.

Something to add to the list possibly, but with all the people having the issue this hasn't fixed it

Thanks

Just to add perspective we had an issue with the headlight relay on our 2006 Trailblazer and changing it fixed the issue...

When you are towing you use more fuel so the pump is working harder therefor MORE current is being used, more current means more HEAT thru relay....

 

[puckhead]

I ended up getting rid of mine. I didn't change the fuel pump, maybe I should have! I did wrap my fuel rails and it didn't do anything.

 

[syclnjr]

Just to add perspective we had an issue with the headlight relay on our 2006 Trailblazer and changing it fixed the issue...

When you are towing you use more fuel so the pump is working harder therefor MORE current is being used, more current means more HEAT thru relay....

Ok again thanks for the thought , but when it just died at a light after towing on the highway, the first thing that I checked was if the fuel pump was coming on, it was... so relay is likely not an issue in this case.

With the history of this issue and what others have been seeing fuel delivery, in reference to the pump hasn’t been an issue.

 

[syclnjr]

I ended up getting rid of mine. I didn't change the fuel pump, maybe I should have! I did wrap my fuel rails and it didn't do anything.

Thanks for the response to this, that is where I am at with mine, if I can’t figure it out it’s getting sold.

 

[syclnjr]

This has been discussed before I thought the general consensus it was it is due to fuel vaporization? when this happens try releasing some fuel at the schrader valve on the intake and see if it starts again without waiting.

Thanks and sorry I missed your comment on this.

Agree on the general consensus, wrapping the fuel lines seems to be the best thing to take care of the issue. Read through the entire thread again last night.

I have to crawl under the truck and look as to the best method to wrap the lines, I bought 3/4 inch fire proof sleeve and my thought was to disconnect the fuel line at the rail and possibly slide it down the line, but I believe there is a brake on the back side that will hold that up.

anyone still around that has done this?

thanks

 

[Geotrash]

Wrapping the fuel rails as a solution doesn’t make sense to me. Even if the fuel rails were to reach 200°F, the vapor pressure would still be about than 14 psi if my calculations are correct. And the fuel pressure while running on these trucks, should be between 40 and 50 psi - more than enough to maintain gasoline liquidity even at much higher temperatures.


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