Dying on idle.

[2007 Denali XL]

My 2007 Yukon XL (145K miles) has just returned with a brand new transmission after sitting for 3 months. Transmission is working well but there is another issues I am trying to work out.

After driving the car for about 30 mins (up and down hills, I live in the mountains), I park the car for a short period (pop into the store) and when I come back and attempt to start it, no dice. The car turns over strong and we have 100% electrics extra but it will not start. Wait about 3-5 minutes and crank again, 2 or 3 times and bingo we have lift off.

I get going and drive home and on the drive it's running tiny bit rough, but you would need to know the car well to feel it, my passengers cannot feel anything wrong. I park at home and leave it idling, roughly and after a few mins it just dies all by its self.

I have repeated this 3 times always with the same issues.

The only thing I have done so far is to clean the throttle body which was pretty gunked up, I thought I had fixed it but no, same thing again.

The car starts strong after a couple of hours sitting and drives fine before the issue starts.

In summary, Car starts well, drive 30 mins up big hills, hot sun. Park, no restart after 5 mins, keep cranking and it will start. Get home, leave it to idle and it dies.

What should I check next?

Thanks in advance.

 

[dwinters14]

Any codes? Sounds like it could be plugs (just from a generic car guy perspective) the Yukon pros will probably have more specific advice.

 

[2007 Denali XL]

Any codes? Sounds like it could be plugs (just from a generic car guy perspective) the Yukon pros will probably have more specific advice.

Thanks, but no codes or check engine light appearing either

 

[OR VietVet]

A fuel pressure test and drive with a gauge you can see is needed or monitor with a Tech 2 during the drive and hot soak start attempts.

 

[2007 Denali XL]

A fuel pressure test and drive with a gauge you can see is needed or monitor with a Tech 2 during the drive and hot soak start attempts.

thanks,

I don't know how to do a fuel pressure test, I will look online.

What sort of gauge are you referring to?

I do not have a Tech 2

What is a hot soak?

Would it be adviseable to swap out the plugs as a first step?

 

[OR VietVet]

I say no to the new plugs but new plugs can't hurt anything. A hot soak is when the engine is completely warm and then shut off the engine and the heat in the engine will rise because the fan is not pulling air across the radiator and until it sits long enough the temp goes up and then starts to drop after a period of time. If the electric fans are ran by a sensor then they may stay on for a period of time after you shut off the engine and will prevent that temp climb. If you can go to Harbor Freight and get an inexpensive fuel pressure gauge and make sure it has additional extensions that allow for the gauge hook up and snake out under the back of hood and tape to windshield so you can watch the pressure during driving and engine shut off and engine restart. The gauge attaches at a shrader valve in the fuel injection fuel line on top of the engine. The shrader valve is like a tire valve but is permanently mounted on the fuel rail. Watch a couple of you tube videos to get the jest of what I am saying. Report back here with the readings.

 

[2007 Denali XL]

I say no to the new plugs but new plugs can't hurt anything. A hot soak is when the engine is completely warm and then shut off the engine and the heat in the engine will rise because the fan is not pulling air across the radiator and until it sits long enough the temp goes up and then starts to drop after a period of time. If the electric fans are ran by a sensor then they may stay on for a period of time after you shut off the engine and will prevent that temp climb. If you can go to Harbor Freight and get an inexpensive fuel pressure gauge and make sure it has additional extensions that allow for the gauge hook up and snake out under the back of hood and tape to windshield so you can watch the pressure during driving and engine shut off and engine restart. The gauge attaches at a shrader valve in the fuel injection fuel line on top of the engine. The shrader valve is like a tire valve but is permanently mounted on the fuel rail. Watch a couple of you tube videos to get the jest of what I am saying. Report back here with the readings.

Roger all that, will report results.

 

[2007 Denali XL]

I say no to the new plugs but new plugs can't hurt anything. A hot soak is when the engine is completely warm and then shut off the engine and the heat in the engine will rise because the fan is not pulling air across the radiator and until it sits long enough the temp goes up and then starts to drop after a period of time. If the electric fans are ran by a sensor then they may stay on for a period of time after you shut off the engine and will prevent that temp climb. If you can go to Harbor Freight and get an inexpensive fuel pressure gauge and make sure it has additional extensions that allow for the gauge hook up and snake out under the back of hood and tape to windshield so you can watch the pressure during driving and engine shut off and engine restart. The gauge attaches at a shrader valve in the fuel injection fuel line on top of the engine. The shrader valve is like a tire valve but is permanently mounted on the fuel rail. Watch a couple of you tube videos to get the jest of what I am saying. Report back here with the readings.

is this a suitable Pressure Tester, will the hoses be long enough?

https://www.amazon.com/Detool-Press...pY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU&th=1

 

[Doubeleive]

is this a suitable Pressure Tester, will the hoses be long enough?

https://www.amazon.com/Detool-Pressure-Injection-Accurate-Reading（Master）/dp/B07C5LZBTX/ref=sr_1_1_sspa?dchild=1&keywords=fuel+pressure+gauge+kit&pd_rd_r=ed0c7017-6b9d-41e7-bc60-ad9f4482a2da&pd_rd_w=sWd7X&pd_rd_wg=4mz8S&pf_rd_p=0ec05f25-9534-48fe-9c3e-40b89957230e&pf_rd_r=RB5AM1145J6GVHK66284&qid=1594515411&sr=8-1-spons&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExTkRPQVdONzhEUk9KJmVuY3J5cHRlZElkPUEwOTA0ODExMzNGQlBGVlVYOUlZNyZlbmNyeXB0ZWRBZElkPUEwMjY1NzY1MldNOFZQOVhEN0FFNSZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU&th=1

ya that's the standard run of the mill kit, should be just enough room to wedge it thru the hood opening if you want to monitor it while driving but it sounds you will be able to just let it idle and rule it in or out.

 

[2007 Denali XL]

ya that's the standard run of the mill kit, should be just enough room to wedge it thru the hood opening if you want to monitor it while driving but it sounds you will be able to just let it idle and rule it in or out.

cool thanks