Dying on idle.

[BG1988]

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.

check the MAF sensor that can cause long cranking

 

[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.

Got Pressure testing Kit,

Engine Cold - Ignition on = 45psi
Engine Cold - Car running = 62psi

Have not performed hot soak test yet.

Kit did not provide enough hose to be able to read while driving, looking for a suitable extension hose.

 

[Doubeleive]

Got Pressure testing Kit,

Engine Cold - Ignition on = 45psi
Engine Cold - Car running = 62psi

Have not performed hot soak test yet.

Kit did not provide enough hose to be able to read while driving, looking for a suitable extension hose.

did you type that in correctly? it should be the opposite you should have 60-65 ignition on and 45 engine running
if you did type it in correctly then monitor it and see what it does when it dies at idle. if the fuel pressure drops and then it dies then I would suspect the fuel pump, if the fuel pressure stays the same and the engine dies anyway it may be something else.

 

[2007 Denali XL]

Got Pressure testing Kit,

Engine Cold - Ignition on = 45psi
Engine Cold - Car running = 62psi

Have not performed hot soak test yet.

Kit did not provide enough hose to be able to read while driving, looking for a suitable extension hose.

no mistype, but I will check again and load video.

I did release the pressure in the shrader value before connecting the gauge and turning on the ignition, is that the right thing to do?

 

[89Suburban]

Next time you have a no start punch the middle bottom of the fuel tank a few times then try it.

 

[Doubeleive]

no mistype, but I will check again and load video.

I did release the pressure in the shrader value before connecting the gauge and turning on the ignition, is that the right thing to do?

it doesn't matter it will re-charge the line each time you turn the key, i would just monitor it and see what it does

 

[2007 Denali XL]

it doesn't matter it will re-charge the line each time you turn the key, i would just monitor it and see what it does

 

[PNWYukon]

This is from a forum over at CarGurus:

"I had the same problem of stalling with my 2003 Yukon XL 1500. Turned the vehicle on and moved the same wire bundle that runs down beside then under the power steering pump. The engine stalled when I moved the wire bundle up and down. I found a grounding wire coming out of the bundle that was frayed, and broke when I moved it. Fixed the grounding wire. Fixed the problem!"

Since your transmission was replaced, wiring is a definite possibility as the harnesses can be torque or pulled on by the mechanics. People are saying when their rig gets hot too, so check your wiring harnesses and the like for abrasions or shorting areas. Good luck.

 

[2007 Denali XL]

This is from a forum over at CarGurus:

"I had the same problem of stalling with my 2003 Yukon XL 1500. Turned the vehicle on and moved the same wire bundle that runs down beside then under the power steering pump. The engine stalled when I moved the wire bundle up and down. I found a grounding wire coming out of the bundle that was frayed, and broke when I moved it. Fixed the grounding wire. Fixed the problem!"

Since your transmission was replaced, wiring is a definite possibility as the harnesses can be torque or pulled on by the mechanics. People are saying when their rig gets hot too, so check your wiring harnesses and the like for abrasions or shorting areas. Good luck.

thanks, I will check that

 

[2007 Denali XL]

it doesn't matter it will re-charge the line each time you turn the key, i would just monitor it and see what it does

rigged up the fuel pressure gauge to the window. Here is a video showing, running, off, electrics on, start. Will do road test tomorrow followed by hot soak.