Hi all,
I'm having a frustrating issue with my 2001 GMC Yukon 5.3L SLT 4x4 that I'm hoping someone can help me identify. I've been noticing for a little while now that pressing the accelerator from idle (such as stopped) that the tach will jump up to about 1,200, then dip slightly as the engine pauses, only to jump back up and run (mostly) fine. I've also started to notice it while moving, say turning, where I am rolling, but at idle, then pressing the accelerator to finish the turn, the same thing happens. While running at speed above, say 2,000 rpm, I see no variations in the tach, it seems rock solid, and the engine runs smoothly. In fact, anything over 1,200-1,300 RPMs seems to not be an issue. At first I thought it was worse after a new start only to get better, but not sure that is the case, and it doesn't do it EVERY time. It also doesn't do it if I'm in park and I "accelerate" to the same RPMs, so being under load seems to be a contributing factor. Idling is very smooth. While testing, I've found that if I cruise slowly at about 1,000-1,200 RPMs (just rolling slowly in a parking lot), that the tach will occasionally dip, like a misfire, but I don't feel it in engine roughness, but do feel the slight deceleration. It never dies on me (except for today, when I was slowly turning into a parking space).
I've been driving this truck almost every day for 25 years, since buying her new, so (as many of you know), I can just hear and feel when things aren't right. It has ~265,000 miles and is in very good condition.
Things I've tried/done recently:
* 11/2026 265k: Cleaned fuel injectors, fuel rails, backflush injectors, test fuel pump, reset fuel adaptives (where applicable), replaced fuel filter
* I've tried various fuel injector cleaners, HEET (water inhibitors/driers, etc.), and none seem to resolve the issue, even temporarily. I buy gas at various places, but much of AK's gas comes from the same places, so it could be that.
Also, in the past:
* 07/2018 232k: Replaced alternator
* 06/2015 199k: replaced Plugs/Wires, replaced fuel filter
* 06/2006 85k: replaced fuel pump, fuel filter, flush fuel system, clean fuel lines
* Changed oil/filter regularly
* Gas cap has been replaced
Check Engine Light is NOT on.
I never have to add oil between changes, and it never smokes, even under heavy acceleration or strain.
I pull a small 2,000 lb trailer during the summer with no issues.
It has never let us down, or left us stranded (which is good, because we live in AK and sometimes we are far from help).
If anyone has experienced this, or has any idea of what I could check next, or at least point me in a general direction, that would be appreciated.
Cheers,
Griz
I'm having a frustrating issue with my 2001 GMC Yukon 5.3L SLT 4x4 that I'm hoping someone can help me identify. I've been noticing for a little while now that pressing the accelerator from idle (such as stopped) that the tach will jump up to about 1,200, then dip slightly as the engine pauses, only to jump back up and run (mostly) fine. I've also started to notice it while moving, say turning, where I am rolling, but at idle, then pressing the accelerator to finish the turn, the same thing happens. While running at speed above, say 2,000 rpm, I see no variations in the tach, it seems rock solid, and the engine runs smoothly. In fact, anything over 1,200-1,300 RPMs seems to not be an issue. At first I thought it was worse after a new start only to get better, but not sure that is the case, and it doesn't do it EVERY time. It also doesn't do it if I'm in park and I "accelerate" to the same RPMs, so being under load seems to be a contributing factor. Idling is very smooth. While testing, I've found that if I cruise slowly at about 1,000-1,200 RPMs (just rolling slowly in a parking lot), that the tach will occasionally dip, like a misfire, but I don't feel it in engine roughness, but do feel the slight deceleration. It never dies on me (except for today, when I was slowly turning into a parking space).
I've been driving this truck almost every day for 25 years, since buying her new, so (as many of you know), I can just hear and feel when things aren't right. It has ~265,000 miles and is in very good condition.
Things I've tried/done recently:
* 11/2026 265k: Cleaned fuel injectors, fuel rails, backflush injectors, test fuel pump, reset fuel adaptives (where applicable), replaced fuel filter
* I've tried various fuel injector cleaners, HEET (water inhibitors/driers, etc.), and none seem to resolve the issue, even temporarily. I buy gas at various places, but much of AK's gas comes from the same places, so it could be that.
Also, in the past:
* 07/2018 232k: Replaced alternator
* 06/2015 199k: replaced Plugs/Wires, replaced fuel filter
* 06/2006 85k: replaced fuel pump, fuel filter, flush fuel system, clean fuel lines
* Changed oil/filter regularly
* Gas cap has been replaced
Check Engine Light is NOT on.
I never have to add oil between changes, and it never smokes, even under heavy acceleration or strain.
I pull a small 2,000 lb trailer during the summer with no issues.
It has never let us down, or left us stranded (which is good, because we live in AK and sometimes we are far from help).
If anyone has experienced this, or has any idea of what I could check next, or at least point me in a general direction, that would be appreciated.
Cheers,
Griz
