Click here to visit LS1Tech
Click here to visit Performance Trucks
Click here to visit Mod Motor Tech
Click here to visit Modern Hemi

PerformanceTrucks.net Forums  

Go Back   PerformanceTrucks.net Forums > GENERAL MOTORS SPECIFIC FORUMS > Tuning, Diagnostics, Electronics, and Wiring
Sign in using an external account
Register Forgot Password?

Welcome to Performance Trucks!
Welcome to Performance Trucks,

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!


Reply
 
LinkBack Thread Tools Search this Thread
Old 01-18-2012, 12:46 PM   #1
Trader Rating: 0
Registered User

 
brock mann's Avatar
 
Join Date: Jan 2012
Location: small town ohio
Posts: 16
Default 2000 Z71 gas mileage issues

I pick up my 2000 Silverado Z71(5.3 auto) last month used with 100,000 miles on.
I have ran several tanks of gas through it and I can only get 13 mpg. It doesn't matter if I romp on it all day, run 400 miles on the freeway,or grampa it around town. I only get beteewn 13.1 & 13.7 mpg. Is this a normal thing?
I bought an Airaid filter kit(200-112-1) and pick up a borla cat back exhaust used. None of this helped. I received a throttle body spacer with the air filter but havent put it on yet.
I have a crane cam(#Hr 208 294 2S 13.55) I bought used on ebay and plan on putting it in when it gets warmer out. I also plan on putting LT headers on about the same time.
The truck is my daily driver. Right now the truck cant dig its way out of its way until you hit about 3500 rpm then hang on. I've always had hopped up s10s in the past so the 5.3 is new to me.
I only get 1 ses code and its for the purge solenoid on the gas tank. It was 100.00 from the parts store. I have to drop the tank to get to the one on this truck.
Thanks for any help on my issues.
__________________
2000 Z71 LT
brock mann is offline   Reply With Quote
Old 01-18-2012, 07:24 PM   #2
Trader Rating: 0
On The Tree
 
Join Date: Jun 2008
Location: Malvern, AR
Posts: 126
Default

Change the fuel filter. It's probably never been changed. Inside the frame, drivers side, between middle of door and tank.
__________________
99 Sierra, 220/220 .581/.581 112, Dynatech headers, True Dual Flowmaster Super 44's, P-1 @ 11psi, 5th 4l60e, Yank 3200, Blackbear Tune.....patiently waiting 80 swap....

06 Sierra Z71, DD
5.3 GMC is offline   Reply With Quote
Old 01-18-2012, 07:45 PM   #3
Trader Rating: 18
TECH Resident
 
chevymec's Avatar
 
Join Date: Jul 2004
Location: Richlands N.C.
Posts: 875
Send a message via MSN to chevymec Send a message via Yahoo to chevymec
Default

Purge valve is on the intake, vent valve is on the tank and you dont have to drop it to replace. I cant get over 13 mpg in my 2000 Z71 so I feel your pain.
chevymec is offline   Reply With Quote
Old 01-18-2012, 08:21 PM   #4
Trader Rating: 28
TECH Junkie
 
TX Tahoe Z71's Avatar
 
Join Date: Nov 2004
Location: Houston, Texas
Posts: 3,705
Default

Change the spark plugs, TR55 gapped at .055". Clean the MAF sensor with the spray you can get at any auto parts store. Fuel filter is a great idea too. Seafoam top end treatment (good write up on LS1tech). If none of that helps, replace the FRONT O2 sensors (even if you aren't getting a code thrown) with AC Delcos or Delphis (forgot which are the good ones, but don't get Chinese or Bosch), check RockAuto.com.

But the biggest difference maker is a tune! Check sponsors on the right, Wheatley, Nelson and Blackbear are all great tuners.

EDIT: Oh, sell the throttle body spacer to help pay for this, that is only good as a paper weight.
__________________
2003 Tahoe Z71 5.3 FlexFuel: Radix MP112 10psi, GT2-3 cam, CTS-V h/e, LPP LT's, Walbro 450, FIC 75#'ers, Wheatley E85 tune, Century Stage 4 4L60E, 300mm 2400 Circle D, '05 fans, 22" Magnaflow, Hotchkis sways, panhard bar, trailing arms, Edelbrock IAS, 3.73s, Yukon LSD, hydroboost, '07 brakes
TX Tahoe Z71 is offline   Reply With Quote
Old 01-19-2012, 06:32 AM   #5
Trader Rating: 0
Registered User

 
brock mann's Avatar
 
Join Date: Jan 2012
Location: small town ohio
Posts: 16
Default

To all.
The fuel filter was changed last year with the fuel pump.
TX Tahoe Z71 I'll look for seafoam. I've used it on carb cars but never FI cars. I will also try cleaning thethe MAF.
Dumb question what brand plug? AC Delco?
chevymec I look on truck in the yard and it was on the middle of the frame, but mine isnt. I am guessing that it is located on or close to the frame. Really 13mpg even on the highway? The previous owner said he'd get 22 mpg on the highway. My buddy with a Sierra gets around 24 highway. Hes odd though. He get 100,000 miles out of 80,000 miles tires too. Yes I saw it with my own eyes.lol
Thanks everyone!
__________________
2000 Z71 LT
brock mann is offline   Reply With Quote
Old 01-19-2012, 07:03 AM   #6
Trader Rating: 18
TECH Resident
 
chevymec's Avatar
 
Join Date: Jul 2004
Location: Richlands N.C.
Posts: 875
Send a message via MSN to chevymec Send a message via Yahoo to chevymec
Default

Look behind the drivers side of the cab at the front of the tank. It is a tight fit. I usually always cut the tube off them and with some force yank it out of the holders.
chevymec is offline   Reply With Quote
Old 01-19-2012, 08:57 AM   #7
Trader Rating: 28
TECH Junkie
 
TX Tahoe Z71's Avatar
 
Join Date: Nov 2004
Location: Houston, Texas
Posts: 3,705
Default

Typically, you will see 16-18mpg on the highway in a tuned up Z71 ecsb (extended cab, short bed). I highly doubt your friends were seeing 20 or 22mpg on average unless they were running no A/C on a perfectly level road at 65mph the entire way AND had an aftermarket tune.

Spark plug brand is NGK, TR55 is the plug. Typically want to change them every 20-25k miles to keep it running well.
__________________
2003 Tahoe Z71 5.3 FlexFuel: Radix MP112 10psi, GT2-3 cam, CTS-V h/e, LPP LT's, Walbro 450, FIC 75#'ers, Wheatley E85 tune, Century Stage 4 4L60E, 300mm 2400 Circle D, '05 fans, 22" Magnaflow, Hotchkis sways, panhard bar, trailing arms, Edelbrock IAS, 3.73s, Yukon LSD, hydroboost, '07 brakes
TX Tahoe Z71 is offline   Reply With Quote
Old 01-22-2012, 04:44 PM   #8
Trader Rating: 0
Registered User

 
brock mann's Avatar
 
Join Date: Jan 2012
Location: small town ohio
Posts: 16
Default

I havent installed the cam or headers yet. I'm waiting for the weather in Ohio to warm up. The only mods I've done so far are the air cleaner and Borla exhaust.
__________________
2000 Z71 LT
brock mann is offline   Reply With Quote
Old 01-23-2012, 08:53 PM   #9
Trader Rating: 0
TECH Resident
 
Join Date: Dec 2006
Location: Enid, OK
Posts: 867
Send a message via AIM to oldred95 Send a message via MSN to oldred95 Send a message via Yahoo to oldred95
Default

My 99 got 16-17 all stock on the highway 65-70 mph. If I ran 75-80 on the turn pike it would drop off to about 15-16 mpg. On the last road trip to Dallas running 75 mph through the rolling hills on I35 it managed to get 16.5 mpg. Its taller and wider with bigger tires but it does better mostly due to the fans. My fan clutch seemed to be mostly engaged all the time. The efans really freed it up. I would imagine I could get 18ish if I kept it at 65 and drove nicely. FWIW my daily commute is 24 miles and it gets a consistent 14-15 mpg running 70 mph.
__________________
1995 Chevy ECSB - project truck
99 NBS Silverado - transgo HD2, 3 1/2" cat back, 05+ efans, tuned with Efi Live, leveled, 1 1/2" body lift and 305/70-16 Mickey ATZs
oldred95 is offline   Reply With Quote
Old 01-24-2012, 05:21 PM   #10
Trader Rating: 4
FormerVendor
 
Join Date: Apr 2011
Location: Rock Hill SC
Posts: 688
Default

Quote:
Originally Posted by TX Tahoe Z71 View Post
Typically, you will see 16-18mpg on the highway in a tuned up Z71 ecsb (extended cab, short bed). I highly doubt your friends were seeing 20 or 22mpg on average unless they were running no A/C on a perfectly level road at 65mph the entire way AND had an aftermarket tune.

Spark plug brand is NGK, TR55 is the plug. Typically want to change them every 20-25k miles to keep it running well.
+1
Just get a tune and check the O2's
CalEditor@PCMCalibrators is offline   Reply With Quote
Old 01-24-2012, 05:21 PM
PerformanceTrucks
Ford F150




Paid Advertisement
Reply

Tags
01, 2000, 2012, 99, cam, chevrolet, filter, fuel, gas, installing, mileage, millage, silverado, tuning, z71


Thread Tools Search this Thread
Search this Thread:

Advanced Search

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

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -5. The time now is 02:11 PM.

 



Powered by vBulletin® Version 3.7.4
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.

PerformanceTrucks.net and InternetBrands, Inc. are not affiliated with the Ford Motor Company