Acceleration Issues

[02 Denali-G]

Hello All,

 

New to these forums, but have a question that has me stumped. Just started happening today.

 

I used my 2002 Yukon Denali 6.0L for work and normally other then average wear and tare its a very reliable truck. Today I started noticing a "whinning" noise coming from the drivers side engine area upon acceleration. Honestly, it kind of sounded like a turbo lol. But I figured it would get looked at when the truck goes in for its next tune up on Monday.

 

Later, I picked up my wife and kids to go out and noticed the truck acting very odd on acceleration. It is very gutless, not the raw power the Vortec 6000 was giving as recent as a few days ago. Also it "Lurches" upon acceleration. For example, I went to pass someone on doing about 60 km/h normally at this speed I punch it and am easily doing 100 km/h in the blink of an eye. Now the truck had no power, lurched and struggled as if it was going to stall this lasts for several seconds before the truck finally picks up. If I ease on the gas pedel and accelerate slowly there is no issues.

 

I thought it may be an air issue, I checked the intake and the filter both of which are very clean. I am also suspecting the fuel filter or injectors but if these were the issues then wouldent I see an issue upon intial start up? The truck fires fine, no excess turning. Starts the first time, every time.

 

Thanks in advance and any help is greatly appriciated!

[02 Denali-G]

To add, my fuel milage has recently gone to hell too, well I can't say with a straight face that its ever been great but now its just insane....

 

I also read that the GenIII engines were shipped with a computerized throttle body, and that this throttle body was designed with an extra intake that never got used. The air passing by this extra intake can cause a whistleing (Turbo'ish sound) but this has not really been confirmed, just internet speclulation.

 

Thanks again!

[KMGZ400]

someone else who knows more will shortly chime in, but i definatley know that the front diff's in the GMT800 AWD system always need to be rebuilt due to bearing failure? something like that...

[Carder09]

Unfortunately it sounds like the fuel pump pressure is weak, usually the truck will start fine but when accelerating is where you problem lies, possibly get the pressure checked from your fuel pump to diagnose if that's what's wrong, as for the fly by wire throttle body, computerized yes, some second thing in there is something I have never heard of. And as for the driver side whine, I assume you have checked the power steering pump already, mine has a small whine and needs a flush and refill, that should correct it.

[02 Denali-G]

Thanks Carder!

 

Yeah i know there is an issue with the power steering as I have a loud hissing coming from both wheel wells when turning and during low speed turns its almost as if I have no power steering. Good news is that it was going in to the shop on Monday for a turn up and to have the power steering system checked. Now I just have to add fuel lines, filter, pump and injectors to the list. I have a friend who is a GM mechanic and he is saying that it may just require a good cleaning throught the fuel system. Fingers crossed and pray thats all it is.

[02 Denali-G]

Update: No such luck. Truck died on me at a busy intersection today. I was told by an old timer that you can hit the tank to try and get the pump to start back up. So I tried this before calling a tow truck and low and behold the truck started and ran just long enough for me to get it into the shop. So end conclusion was that the fuel pump was the culprit. $600 and change for an AC Delco OEM installed. Still have to pin point the cause of the whistle sound but I assume that is the power steering pump.

 

Thanks for all your help!

[Carder09]

Dang, that is one expensive A$$ fix!!! But im sure they cleaned out the whole system and such, hopefully, and yeah just check your power steering fluid level and probably needs a flushing and replacing. Good Luck!