00 Silverado Power Loss

[Mod_12]

Have a 2000 Silverado LS z71 4x4 with a 5.3 and 3.73 gears. It has 131,000 miles. I haul a 20ft enclosed trailer every weekend during the summer months. Only carry about 1000# in the trailer. I have not noticed this problem before with towing. The truck is a major dog anymore. Anything below 55mph but when you get above 55mph it takes no time to get to 90. I have recently noticed that when the truck is empty it is still a dog out of hole. Can't smoke tires anymore unless it is wet out. I also used to get 85-90 miles on my trip meter before the gauge would move now I am getting about 50 miles or so. I have done Plugs, Wires, Fuel Filter, fuel regulator, air filter changes, EGR valve. I had the dealer run for codes and there is nothing. I also had the fuel injectors cleaned on there machine. I have noticed at 1500 RPM"S there is a vibration in the motor. It almost feels like it has a bad injector or so. Any Thoughts......

[j cAT]

Originally Posted by Mod_12

Have a 2000 Silverado LS z71 4x4 with a 5.3 and 3.73 gears. It has 131,000 miles. I haul a 20ft enclosed trailer every weekend during the summer months. Only carry about 1000# in the trailer. I have not noticed this problem before with towing. The truck is a major dog anymore. Anything below 55mph but when you get above 55mph it takes no time to get to 90. I have recently noticed that when the truck is empty it is still a dog out of hole. Can't smoke tires anymore unless it is wet out. I also used to get 85-90 miles on my trip meter before the gauge would move now I am getting about 50 miles or so. I have done Plugs, Wires, Fuel Filter, fuel regulator, air filter changes, EGR valve. I had the dealer run for codes and there is nothing. I also had the fuel injectors cleaned on there machine. I have noticed at 1500 RPM"S there is a vibration in the motor. It almost feels like it has a bad injector or so. Any Thoughts......

the O2 sensors require replacing every 100,ooomi....you are well beyond that....

this is NOT my opinion but that of the manufactures...

[Mod_12]

Will that effect the mpg? Last week got 14mpg and this week 13.7mpg. I was getting 18mpg or better last summer. Also has a rough idle after a fews minutes.

[j cAT]

Originally Posted by Mod_12

Will that effect the mpg? Last week got 14mpg and this week 13.7mpg. I was getting 18mpg or better last summer. Also has a rough idle after a fews minutes.

the O2 sensors adjust the fuel mixtures by reporting the exhaust condition...

as i stated 100,ooomi is the replacement interval...you may also have a damaged cat system from incorrect fuel mixture.

these vehicles get 17-20mpg...14mpg is a 2500 6L engine

[jyount]

Originally Posted by j cAT

the O2 sensors adjust the fuel mixtures by reporting the exhaust condition...

as i stated 100,ooomi is the replacement interval...you may also have a damaged cat system from incorrect fuel mixture.

these vehicles get 17-20mpg...14mpg is a 2500 6L engine

Really.....
I'm getting 14 to 15, doesn't seem to run bad though. And I only have about 45k on mine.
I thought the mileage was pretty ******, but didn't think it was that bad. I have only had it about 2 months. I just figured it was pcm programming. Wifes ext tb has the aluminum 5.3 and 3.73 and she gets 17 to 18 town. around 20 highway. But my truck will outrun it, Just thought it was weight and maybe tune, ie shift logic and power, but maybe there is more to it.... is my cr a little more or something?

[jyount]

jcat, think my mpg is off?

[j cAT]

Originally Posted by jyount

jcat, think my mpg is off?

if you have a 1500 4x4 5.3L engine with the eaton 3.73 diff.. you should be getting 17-20mpg on the hwy @60-70mph....87 octane 10% alcohol....

the lower mpg could just be your driving habits...
most 2500 trucks get the 14mpg range...much heavier vehicle..

are you positive that this vehicle has only the stated mileage ?
odometer roll backs are common...did you do a check for this ?

[jyount]

Originally Posted by j cAT

if you have a 1500 4x4 5.3L engine with the eaton 3.73 diff.. you should be getting 17-20mpg on the hwy @60-70mph....87 octane 10% alcohol....

the lower mpg could just be your driving habits...
most 2500 trucks get the 14mpg range...much heavier vehicle..

are you positive that this vehicle has only the stated mileage ?
odometer roll backs are common...did you do a check for this ?

Absolutely positive. Bought it from my wife's uncle, Chevrolet dealer, used, but they sold it and have serviced it since new, I have the records. Its actual.
I have been babying it just to see how much better I could get. Also calculated myself to check the DIC and it is exactly on...


Come to think of it though I honestly have no idea what ratio it has. I am pretty sure it doesn't have 4.10s. Plus they are uncommon in half tons anyhow, don't even know if you can get em.
My wifes has locking 3.73s.
Mine is open.
The only options other then 4.10 would be 3.73 or 3.42 wouldn't it?
3.42 should get better mileage I would think. Plus it doesn't make sense that I would run harder with 3.42 instead of 3.73.

I just crawled under it and looked for a tag on the diff. I looked at my papers and can't find what it is. The door sticker doesn't say, what is the RPO codes. Only thing I know to do is find the RPO in the glovebox.

Any other way to find it?

I know driving habits can be alot, My Jeep TJ with a 4 banger no less went from 12.5 to 16 ONLY because I finally figured out how to shift it.
It doesn't matter if you are full pedal 4th to climb a hill, or very slight pedal 3rd, its still gutless, only difference is mileage, ALOT.

[2000CAYukon]

Post all of the GXX RPO codes from the glove box. Then we can tell you what ratio it came stock with.

//2000CAYukon

[jyount]

Originally Posted by 2000CAYukon

Post all of the GXX RPO codes from the glove box. Then we can tell you what ratio it came stock with.

//2000CAYukon

I found a GU6, that is 3.42 right?
Funny thing is I also found a G80 right beside it, and that is limited slip right? If so the eaton works ALOT better, on slick roads you can swing out my wifes tb very easily, this one just wont. I am pretty sure its open just by driving it, but haven't jacked it up and seen, maybe it does have.

I also have an LM7, already knew that though, as it is the cast iron 5.3

[jyount]

I took a cell picture of my RPO tag, but how do you post it here. On my permissions at the bottom of the page it says

You may post new threads
You may post replies
You may not post attachments
You may edit your posts

[j cAT]

Originally Posted by jyount

I took a cell picture of my RPO tag, but how do you post it here. On my permissions at the bottom of the page it says

You may post new threads
You may post replies
You may not post attachments
You may edit your posts

you have the 3.42 eaton locker diff....because it is the 3.42 I would say that this is not a 4wd vehicle...

if this is the case you should also be getting much more MPG....19-21 with the non 4WD vehicles...

[jyount]

Originally Posted by j cAT

you have the 3.42 eaton locker diff....because it is the 3.42 I would say that this is not a 4wd vehicle...

if this is the case you should also be getting much more MPG....19-21 with the non 4WD vehicles...

It is 4wd. I also don't know what to make of the eaton. It doesn't act at all like it has a limited slip in it.

[jyount]

Originally Posted by jyount

It is 4wd. I also don't know what to make of the eaton. It doesn't act at all like it has a limited slip in it.

The rpo tag my say it, but wet roads today, and every time I pulled out from one road to the other, I hammered on it to try and swing it out, never did anymore than spin one wheel. I know my wife's tb has the eaton, but it 3.73, and if you hammer on it on a wet road you better be ready for it, cause it WILL break loose, everytime, and it has more miles on it than this one, so mine shouldn't be wore out, maybe something broke on it with the previous owner, maybe something with the rear end is the whole reason my mpg is not what it should be....how are these things put together in the locking diffs. Is it limited slip with clutches and steels on the side gears, or is it flywheights like the trac locs or something. If its something I can rebuild for a decent price maybe, I'll tear it apart myself when the weather gets a little better. Rainy and cold right now. Waiting for that April break right now. Quite honestly I am sick and tired of rain and gale force winds all the time. If its gonna be crappy outside, bring it on, atleast I can get the jeep out and play with snow.

[j cAT]

Originally Posted by jyount

The rpo tag my say it, but wet roads today, and every time I pulled out from one road to the other, I hammered on it to try and swing it out, never did anymore than spin one wheel. I know my wife's tb has the eaton, but it 3.73, and if you hammer on it on a wet road you better be ready for it, cause it WILL break loose, everytime, and it has more miles on it than this one, so mine shouldn't be wore out, maybe something broke on it with the previous owner, maybe something with the rear end is the whole reason my mpg is not what it should be....how are these things put together in the locking diffs. Is it limited slip with clutches and steels on the side gears, or is it flywheights like the trac locs or something. If its something I can rebuild for a decent price maybe, I'll tear it apart myself when the weather gets a little better. Rainy and cold right now. Waiting for that April break right now. Quite honestly I am sick and tired of rain and gale force winds all the time. If its gonna be crappy outside, bring it on, atleast I can get the jeep out and play with snow.

the diff you have should be the 3.73 eaton locker on the 4X4 5.3L engine...

the locker allows both wheels to rotate independently until one wheel rotates faster than the other..then the wheels lock up together.,,,until about 100 rev's...then it will release if the slip is gone..

it is possible the previous owner removed this locking mechanism because it was damaged...

bring to a repair shop familiar with this diff and have them check it out...if you need a new diff this must be carefully broken in so that the gear teeth will not get heat damaged..

this diff requires fluid/cover remval/cleaning every 30-40,ooomi....
also when NEW the diff fluid must be replaced at about 1-2000mi so that the breakin debris and heat damaged fluid is serviced.