2007 Denali Rough Idle and Stall After Running Long

[General Stalin]

So you think the problem is more likely still my cats/O2 sensors than it is my fuel pump/fuel system?

 

[swathdiver]

So you think the problem is more likely still my cats/O2 sensors than it is my fuel pump/fuel system?

Get hold of that Tech2 again and check your fuel pressure, see if the pressure drops more than 5 psi in a minute with the pump off. Test the injectors, turning them on and off and see if they are leaking, bleeding down the pressure.

 

[General Stalin]

If I end up having to put a new pump in this tank does anyone have a recommendation (brand/model)? There are quite a few available for this truck on Rockauto.

 

[Rocket Man]

AC Delco OE was my choice when I did mine. I always like OE stuff for hard-to-get to stuff especially. I don't want to do it again any time soon. My original lasted for 160k miles.

 

[Doubeleive]

X2 go oem on the fuel pump

 

[swathdiver]

X3, GM Original Equipment Always! Check your tank straps and lines as best you can before ordering.

 

[General Stalin]

Update: prior to buying any parts or turning any wrenches I rented a fuel pressure tester to see if I could find evidence of poor fuel delivery. Bingo.

Key on and engine off showed pressure jumping to about 50psi for a split second then quickly dropping down to about 20psi over a 30 second period. Engine on my pressure was reading 80+psi which is way above normal. The fuel pump should be pushing at 55-60psi in my vehicle. Regulator may have died, either way I needed a new pump.

Ordered it Monday night from RA, it arrived Wednesday night, I had it installed Thursday afternoon. Checked pressure after install: 60psi steady.

Haven't done quite enough driving in the conditions that would replicate the issue I was having, so I can't say yet whether or not this fixed it. Will update after more road time.

 

[gpracer1]

Im sure your fuel trims were all jacked up from constant pressure changes while driving. I would reset that / batt disconnect, then drive it and let it relearn.

 

[General Stalin]

I disconnected the battery when performing the install so the ECM would have already relearned. Should be all set. Fingers crossed this fixes the issue once and for all.

 

[Rocket Man]

Update: prior to buying any parts or turning any wrenches I rented a fuel pressure tester to see if I could find evidence of poor fuel delivery. Bingo.

Key on and engine off showed pressure jumping to about 50psi for a split second then quickly dropping down to about 20psi over a 30 second period. Engine on my pressure was reading 80+psi which is way above normal. The fuel pump should be pushing at 55-60psi in my vehicle. Regulator may have died, either way I needed a new pump.

Ordered it Monday night from RA, it arrived Wednesday night, I had it installed Thursday afternoon. Checked pressure after install: 60psi steady.

Haven't done quite enough driving in the conditions that would replicate the issue I was having, so I can't say yet whether or not this fixed it. Will update after more road time.

Might have just been the FPR but since they moved them to the fuel pump assembly you might as well just replace the pump while you're there. I was having an issue with my 02 after installing my blower where I would have to crank it for awhile at times to start it or else prime it by cycling the key a couple times because my pressure was bleeding off after I shut it down. It was the regulator and I was able to buy a rebuild kit for $15 and fix it in 20 minutes. That isn't possible with the newer vehicles. Of course, 2 weeks ago the damn pump quit on me anyway. Glad to hear it looks like you got it fixed.

 

[General Stalin]

One last update: have put a couple thousand miles on my truck since the install and it's been running flawlessly, including during long drives in stop/go traffic in 90°+ heat.

The fuel pump 100% fixed the issue I was having that I started this thread about.

 

[swathdiver]

Still burning oil?

 

[General Stalin]

Yes, have not addressed that yet but it's on the to-do list. For what it's worth I feel like it burns a somewhat normal amount of oil for a motor with over 200k miles.

 

[swathdiver]

Yes, have not addressed that yet but it's on the to-do list. For what it's worth I feel like it burns a somewhat normal amount of oil for a motor with over 200k miles.

I do not remember if this was mentioned or asked before, do you have the updated driver's side valve cover? It prevents oil loss.

 

[General Stalin]

Did not know that was a known issue with these engines, although valve covers we're an avenue I was going to check for oil consumption.

 

[jrmax88]

hey guys and girls. i have read dozens and dozens of posts about this issue. well i have found the ANSWER!!! the reason no one has found it is because everyone has been changing parts and not pulling the trucks apart. go to your crank position sensor unpolug it and open up that harness. you will find the 3 wires fused together. they only affect the engine when hot. get a new pigtail, install individually tape each wire and problem solved-guaranteed.

 

[wsteele]

hey guys and girls. i have read dozens and dozens of posts about this issue. well i have found the ANSWER!!! the reason no one has found it is because everyone has been changing parts and not pulling the trucks apart. go to your crank position sensor unpolug it and open up that harness. you will find the 3 wires fused together. they only affect the engine when hot. get a new pigtail, install individually tape each wire and problem solved-guaranteed.

Did you read post number 31?

That was posted almost three years ago?

 

[General Stalin]

Yeah the fuel pump was the issue. 3 years later the truck still runs like a top have not had this issue pop up again since replacing the fuel pump. I've put about 50k miles on this truck since then.

 

[wsteele]

Yeah the fuel pump was the issue. 3 years later the truck still runs like a top have not had this issue pop up again since replacing the fuel pump. I've put about 50k miles on this truck since then.

Did you ever figure out the oil burn?

I assumed you read about the oil consumption TSB on early AFM engines and dealt with it as well.

 

[General Stalin]

Did you ever figure out the oil burn?

I assumed you read about the oil consumption TSB on early AFM engines and dealt with it as well.

To this day still haven't tackled the oil issue. I'm unaware of and service bulletins related to oil issues with my motor, got a link?

Recently had to replace ring and pinion on my front differential so I've been trying to hold of on putting more money into the truck for a minute. It still leaks a little oil at about the same rate (hasn't gotten worse) 50k miles later - though my fuel mileage has gotten noticeably worse over the past year or so.