The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 99-06 GMT800 Chevy and GMC Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 09-22-2019, 03:17 PM   #1
VentureRick
Registered User
 
VentureRick's Avatar
 
Join Date: Nov 2009
Location: Belleville, Michigan
Posts: 32
PO171 and PO174

I have a 2002 1500HD with a 6.0 with 133000 miles on it, a couple of days ago it started running really bad but no check engine light came on, I was able to drive it back home and hooked the scanner up and it through these 2 codes, I cleaned the MAS air flow sensor and replaced the air filter and it ran fine so I cleared the codes and drove it a few miles then it developed a slight hesitation off of idle, I have checked for vacuum leaks and have not found any, checked the fuel pressure and its only running 25 to 30 pounds with vacuum line unhooked at the regulator, I changed the regulator and it still reads the same, what should the fuel pressure be and is there a certain way your supposed to check it, thanks in advance,
__________________
Rick


69 SWB Project
95 Suburban Daily Driver
47 Flxible Motor Home 427 GMC 4spd Allison
71 C-10 LWB 307/350 (parted out)
64 SWB Custom Cab 283 powerglide (sold)
2000 Yamaha Venture
VentureRick is offline   Reply With Quote
Old 09-22-2019, 05:28 PM   #2
Palf70Step
State of Confusion!

 
Palf70Step's Avatar
 
Join Date: Jul 2002
Location: Gulfport, MS USA
Posts: 46,575
Re: PO171 and PO174

Have you check for intake manifold leaks? I have also heard an exhaust leak before the first O2 sensor(s) can cause that lean condition issue.
__________________
Bill
1970 Chevy Custom/10 LWB Fleetside
2010 Toyota Tacoma PreRunner SR5 Double Cab - DD

Member of Louisiana Classic Truck Club (LCTC)

Bill's Gallery
Life isn't tied with a bow, but it's still a gift.
Live simply. Love generously. Care deeply. Speak kindly. Leave the rest to God!
Palf70Step is offline   Reply With Quote
Old 09-22-2019, 07:12 PM   #3
AussieinNC
Moderator
 
AussieinNC's Avatar
 
Join Date: Jun 2017
Location: Cherryville, NC
Posts: 2,152
Re: PO171 and PO174

Key on, engine not running, fuel pressure should be 55-60 lbs
Turn key off and fuel pressure should not drop by more than 5lbs...
25 to 30 running is way too low....its a wonder it runs at all...

Sounds like a bad fuel [pump or bad fuel pressure sensor....my money is on the fuel pump...
__________________
Family and country before all others...

2006 Chevy Silverado (Daily Driver)
2012 Chevy Equinox

AussieinNC is offline   Reply With Quote
Old 09-27-2019, 08:47 PM   #4
VentureRick
Registered User
 
VentureRick's Avatar
 
Join Date: Nov 2009
Location: Belleville, Michigan
Posts: 32
Re: PO171 and PO174

Ok I found out the fuel pressure tester I was using wasn't reading right, my pressure is 55 not running, I did change the fuel filter and it has been running great, thanks for the help.
__________________
Rick


69 SWB Project
95 Suburban Daily Driver
47 Flxible Motor Home 427 GMC 4spd Allison
71 C-10 LWB 307/350 (parted out)
64 SWB Custom Cab 283 powerglide (sold)
2000 Yamaha Venture
VentureRick is offline   Reply With Quote
Old 10-26-2019, 09:38 PM   #5
truckdude239
Senior Member
 
truckdude239's Avatar
 
Join Date: Sep 2005
Location: Lewisville, Nc
Posts: 10,216
Re: PO171 and PO174

Mine did same thing turned out to be intake gaskets
__________________
David fuller
Ase Certified Mechanic
Click here to help support our board!!


1971 Chevy c-10 under going a 4.8l LSx swap

Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=421305

2007 Honda Accord my daily 145kmiles
2002 Honda Accord 4 door With 330k(sisters car)
2005 toyota Avalon 228k( brothers car)
2002 Sububran 5.3 245k
2000 Tahoe 5.3l 378

General manager for Marco's Carwash & lube
truckdude239 is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

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

Forum Jump


All times are GMT -4. The time now is 04:10 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com