The Diesel Page Forums

2020 - TDP's 24th Anniversary
What's New | Feature Articles | Product Reviews | Member's Area | Free Forum Registration
Duramax 6600 Diesel Page | Advertiser's Section | Classified Ads | The Diesel Page - Publications

Go Back Forums > 2001 - Current Chevrolet & GMC 2500HD/3500 Light Trucks > Duramax 6600

Duramax 6600 Welcome to the Internet's first Duramax 6600 diesel discussion forum for the LB7, LLY, LBZ, LMM, LML, LGH & L5P RPO code engines. Tips on performance, fuel economy, troubleshooting and more.

Thread Tools Display Modes
Old 07-27-2020, 10:30 PM
Lb7x2 Lb7x2 is offline
Join Date: Jul 2020
Location: USA Maine Washington county
Posts: 1
Default LB7 lacking power

Just posted a large thread but it didn’t seem to post...

I have two LB7’s one is a 2001 and one is a 2002. The 2001 seems to have less power than my 2002. I noticed a manifold leak and I had replaced the manifold. I’ve gained some power and you can actually hear the turbo spooling now. My 2002 LB7 pulls harder and the 2001 seems to struggle more to get up and going. Besides the manifold leaks the only other thing I’ve noticed is one of the rubber fuel lines on top of the fuel filter housing has a slight leak. If the truck sits for a week or so it has to be primed before it will start.

I’m sure there’s many other variables for this issue so I’m just reaching out for ideas. Thanks!
Reply With Quote
Old 07-28-2020, 06:42 AM
DmaxMaverick's Avatar
DmaxMaverick DmaxMaverick is offline
Join Date: Apr 2001
Location: CA
Posts: 12,676

Welcome aboard!

First, if you have issues that have a high probability of causing power loss, chasing a power loss is pointless until all of the issues are addressed and eliminated. The fuel system is very tolerant of air leaks, but they can cause running issues, including power loss. The fuel system doesn't have a lift pump (suction from the tank to the high pressure pump), so any leak you can actually see is a large leak. Having to prime the system after a short period is a firm indicator. Most air leak conditions are not readily visible, even when the system is pressurized (by external means or an added lift pump).

That out of the way, two seemingly identical trucks rarely are really identical, especially after nearly 20 years of service. Many factors coming into play, including but not limited to, tire pressure, actual curb weight (20 years of dirt in the chassis adds up), parasitic losses (alternator, A/C compressor, etc.), intake system restrictions, overall fuel system health, electronic interference/compensation (PCM adjustments for issues not yet serious enough to trigger complaints), operating temperature (real or perceived), sensor errors (MAF, etc.), fan clutch, dragging brakes, etc. For example, something as simple and easily dismissed as a weak/failing battery can cause enough additional load on the alternator, or a weak fan clutch, fouled cooling stack or worn-out thermostats (on the more powerful truck), can cause a perceptible power loss. Also consider not all trucks sound the same, and one may simply sound faster than the other (a stretch, but a real one).
1985 Blazer 6.2
2001 GMC 2500HD D/A
2014 Chevy Cruze Diesel - Fabulous car, no problems at all, but sold Nov. 2016 @ 55K miles.
Reply With Quote

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

Similar Threads
Thread Thread Starter Forum Replies Last Post
2004 lb7 loss of power dins1 Duramax 6600 13 02-04-2020 02:19 PM
How will 2007 LBZ feel to me compared to my former 2002 LB7? LyndaSuzan Duramax 6600 44 04-15-2011 11:01 AM
03 Lb7 Boost Issue Please Help!!!!!!! SSDIESEL Duramax 6600 6 01-24-2008 05:25 PM
Blue smoke, low power worldf 6.2L Diesel - Tech Support - Troubleshooting - Performance 3 09-27-2007 04:17 PM

All times are GMT -7. The time now is 10:23 AM.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, vBulletin Solutions Inc.
Copyright 1996-2020 by - All Rights Reserved