1999 Z-71 5.3 - Loss of power

[jbwalt3]

Hi again, second post, long-time reader of the forum.

I have a 1999 z-71 ext cab 5.3 with 119k. I have recently began considering selling the truck for something more powerful. I don't feel like my truck has as much power as my parents' 05 Suburban or my dad's 03 Tahoe. I have quite a bit more miles than they do though. Is there any specific course of action I should take with 119k to restore the original power of the truck? I drive it lightly, alot of highway but very very minimal towing or load bearing trips. I appreciate any recommendations or input.

Also, I think the truck tends to slightly, very slightly, hesitate when accelerating. It just doesn't feel fresh anymore, and I feel like I need to do something about it.

Thanks again!

[kahjdh]

I have a k&n fipk and duals, it will move when i want it to. Maybe your trans is the issue

[ukrkoz]

just run 2 cans of seafoam through 2 tankfuls and clean throttle intake around pintle valve with toothbrush and some carb cleaner.

fair warning: if you are chasing power, you are chasing ghosts. there's never enough.

be prepaired to selling this truck for peanuts. market is overflowing with "hot air haulers" ridding of their trucks. check any craigslist listings for your area.

[sierra99]

Originally Posted by jbwalt3

Also, I think the truck tends to slightly, very slightly, hesitate when accelerating. It just doesn't feel fresh anymore, and I feel like I need to do something about it.

Thanks again!

Hey there, I also have a 99 silverado z71. Lately I was noticing that when I stepped on it to pass somebody on the interstate, that I would bog down or hesitate a little. I could feel a pretty definite lack of performance. I changed out my fuel filter and it seemed that if I had a full tank of gas, I would do better in performance, but not much. Then my fuel pump finally went out. I replaced it with a Delphi Pump (OEM) and I now have ALL of my power back.
My truck seems new again. Not that I want to, but I can spin my tires with little or no effort, just like when I bought it.
It may be a god idea to check your fuel pressure and make sure you are getting the proper pressure.

I always thought that a fuel pump either worked or did not work. This is definitely not the case. when you say that you do not have the power like the newer tahoe. What exactly do you mean? Give some instances.

Now when I gun it to pass on the interstate, I get put back in my seat again, no hesitation at all. This may be something to look into

[sierra99]

Oh yeah, I forgot to mention I have 144,000 miles on my silverado, and changed out the fuel pump at 143,500 miles.

[jbwalt3]

Originally Posted by sierra99

when you say that you do not have the power like the newer tahoe. What exactly do you mean? Give some instances.

They just feel like they have more power in general, quicker and stronger. Maybe just more advanced versions of the vortec as they worked some bugs out. I could be wrong, but they just feel more alive.

I have replaced my fuel pump and fuel pressure regulator. Did you see a big difference when replacing your fuel filter? I may do this next. Also, have you ever changed your plugs or done any kind of tune up on the truck? I just want it to feel like it did when I got it, not like a worn down 120k truck,

I appreciate your advice. thanks in advance

[semisendiz]

I too lost power a couple of times on my 6.0L 2001 HD, until fuel pump finally gave.
Replaced last week, new fuel filter, and running good as new (150 Kmiles).
Seems you might want to check fuel pressure at the rails. Mine should run at around 50 psi's, it was putting out only 10.

[MT-2500]

Originally Posted by jbwalt3

They just feel like they have more power in general, quicker and stronger. Maybe just more advanced versions of the vortec as they worked some bugs out. I could be wrong, but they just feel more alive.

I have replaced my fuel pump and fuel pressure regulator. Did you see a big difference when replacing your fuel filter? I may do this next. Also, have you ever changed your plugs or done any kind of tune up on the truck? I just want it to feel like it did when I got it, not like a worn down 120k truck,

I appreciate your advice. thanks in advance

If never tuned up I.
I would give it a good full tune up with ac-Delco parts.

[wafrederick]

It could be a plugged up cat too and I have seen this happen after an engine swap.A plugged up cat will take out a 5.3 if not taken care in time.

[waitingforcolumbus]

My '99 has a clutch fan and I think later trucks have electric fans. Electric fans would be one of the few things that would free up some horsepower, they claim 17 hp, and still improve gas mileage, again they claim 2-3 mpg. Flex-A-Lite can be alot of money, Summit has them for $550. Some people in this forum have used Camaro fans with success.

[brandon200317]

Originally Posted by waitingforcolumbus

My '99 has a clutch fan and I think later trucks have electric fans. Electric fans would be one of the few things that would free up some horsepower, they claim 17 hp, and still improve gas mileage, again they claim 2-3 mpg. Flex-A-Lite can be alot of money, Summit has them for $550. Some people in this forum have used Camaro fans with success.

Where on earth did you read it claims 17 hp? a/c compressors don't even claim that much.. if its claiming that much you have a bad clutch. thing is, put an electric fan in, it might take physical load of the engine but it puts more load on the alternator when kicking in which also pull power from the engine.. the benefits are very minimal. i'm with them on the fuel pump check that out and also theres not much to do on a tune up anymore but new fuel filter, check plugs and wires, that's about it.

[budsy47]

I too had a similar problem...01 Z71 4x4 5.3l just didn't seem to be the same @ 130,000km....warmed up engine...1/3 can seafoam in brake booster hose..put the rest in the tank...let it sit 20min...fired it...big smoke...drove it & punched it hard a few times..changed the plugs & wires....cleaned MAF....new fuel filter...cleaned Throttle Body...very black...almost new again...put RP in engine & rear...dropped tranny pan & changed filter...topped up with RP. TB seemed to be the biggest improvement. Life is good again..mileage & throttle response also much better.

[brandon200317]

Originally Posted by budsy47

I too had a similar problem...01 Z71 4x4 5.3l just didn't seem to be the same @ 130,000km....warmed up engine...1/3 can seafoam in brake booster hose..put the rest in the tank...let it sit 20min...fired it...big smoke...drove it & punched it hard a few times..changed the plugs & wires....cleaned MAF....new fuel filter...cleaned Throttle Body...very black...almost new again...put RP in engine & rear...dropped tranny pan & changed filter...topped up with RP. TB seemed to be the biggest improvement. Life is good again..mileage & throttle response also much better.

RP?

[budsy47]

Originally Posted by brandon200317

RP?

RP is Royal Purple....they make synthetic oils. Kind of pricey if you live in Canada. I have changed all fluids out to RP...can't say I get huge power or mileage increase but I do feel I get some small improvement...besides I have to keep my truck & I want the better value of synthetic's....I do tow a bit in the summer....I do rear once a year, drain tranny pan once a year & top up & change oil @ around 8000km or so other diff's every 2 years, fuel filter once a year which I will do twice a year now.

http://www.royalpurple.com/

[j cAT]

Originally Posted by budsy47

RP is Royal Purple....they make synthetic oils. Kind of pricey if you live in Canada. I have changed all fluids out to RP...can't say I get huge power or mileage increase but I do feel I get some small improvement...besides I have to keep my truck & I want the better value of synthetic's....I do tow a bit in the summer....I do rear once a year, drain tranny pan once a year & top up & change oil @ around 8000km or so other diff's every 2 years, fuel filter once a year which I will do twice a year now.

http://www.royalpurple.com/

I have found that in my vehicles operation that, 30,000mi is the correct interval for replacing... I cut open the filter and inspect...I can still see 50% of the filter media still clean and light passes..with the other portion dark with fine debris.


This not to say that others may have to do this twice a year...what should be done is, to see the filter condition, to determine how YOU must handle this very variable maintenence item..

the repair manual states "replace as needed" thanks MR GM for that very helpful suggestion...


with your maintenence intervals you will have few problems... but remember electric motors wear out ....pumps fail to pump the correct pressure because the pump materials are worn....this item appears to fail at around 150-200,ooomi.....if you drive around on empty maybe 10,ooomi..


If the fuel you buy has dirt in, it the pump will fail much faster...