Lack of power? - Diesel Place : Chevrolet and GMC Diesel Truck Forums
 
Home Forum Market Place Garage Tuning Library DTC Tool Register Vendors
Go Back   Diesel Place : Chevrolet and GMC Diesel Truck Forums > GM Diesel Engines > 6.2L Diesel Engine
Register FAQ Forum Rules My Replies My Threads Mark Forums Read Advertise

6.2L Diesel Engine Discuss the 6.2 GM diesel engine & associated components.

DieselPlace.com is the premier Duramax Diesel Forum on the internet. Registered Users do not see the above ads.
Like Tree7Likes

Reply
 
LinkBack Thread Tools
Old 05-25-2012, 11:51 PM   #1 (permalink)
smokinblazer
Clutch
 
smokinblazer's Avatar
 
Join Date: Feb 2012
Posts: 52
iTrader Score: 0 reviews

Lack of power?

I know the 6.2 is not a powerhouse engine but it just seems like its lacking some power. I had an 83 Jimmy several years ago, 700r4, unknown gears, 32x11.50x15 that ran great. My current K5 is an 89, 700r4, 3.42, 31x11.50.15 starts easy, no smoke, runs good, just seems to be lacking some power. Currently has 186k miles and the last 6k by me. So first 180k I have no knowledge of the maint history. I have read on here that if anything past half throttle has no change in performance the lift pump could be bad? I have no change in performance past 3/4 throttle. About every 3-4 tanks of fuel I treat it with Lucas fuel treatment. About 4 tanks back I put about half a bottle of seafoam in the fuel to see if that would help any. Since then when I get down to about 3/8 of a tank it surges/cuts out? while driving like its low on fuel, fill it up and all is fine again. Before the seafoam treatment i have ran it down to 1/8 of a tank before. Not sure if this is any connection but trying to give as much back ground as possible. But since I purchased the Blazer I have thought it did lack a little power. Also from a dead stop in dirt it barely turns the dirt over, not really spinning the tires, kinda like it lacks throttle response. Like I said I know its not a power house engine, but it does seem like its lacking a little bit. Any ideas? Suggestions to check? I am pretty mechanically inclined but don't have alot of diesel specific tools like for checking timing.

__________________
89 K5 Blazer 6.2 Diesel
700r4
3.73 gears
33x12.50x15
Offline  
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Old 05-26-2012, 12:20 AM   #2 (permalink)
surprised
Diesel Starter
 
Join Date: Dec 2011
Location: Benson, Utah
Posts: 197
iTrader Score: 0 reviews

Lift pump can't hurt, is cheap insurance even if it isn't the cure. Have you checked the timing? If no real cause is found, I submit that you might have a much more restrictive muffler this time than your previous experience. Switching mine to dual exhaust made a very noticeable improvement to performance, much more than my follow-up improvements to the intake side.

Offline   Reply With Quote Quick reply to this message
Old 05-26-2012, 02:54 AM   #3 (permalink)
happypunch
Diesel Expert
 
happypunch's Avatar
 
Join Date: May 2011
Location: Boise, ID
Posts: 2,980
iTrader Score: 0 reviews

Old School Oil Burners (Old SOBs) Member

test your lift pump by cracking open the air blead valve on the fuel filter. if it shoots pretty far, then all is well. if it is kinda pathetic, that is a problem. have you changed the fuel filter? that is a big power robber and make sure the air filter is good.

you probably have a c-code intake and egr... if so, get rid of it! at least strip out the egr. a j-code intake would be a good idea too.

i like seafoam, its helped several of my vehicles but it may have broken up some gunk in the tank so double check the filter! and while seafoam will help clean injectors, it wont fix any worn out ones. they should be rebuilt/replaced every 100k so you might be over due for some work. you could always pull them and have them pop-tested. most shops charge for that service, but you might find a tractor supply or something that might do it for free.

you have some decent gearing for good mileage, but wont start very quickly or tow well. i would just start with the basics and then move up the list.
__________________
1987 V20 Suburban 6.2 diesel
GM-3 Turbo
Built 4l60
3.73's With 285/75/16's

Gave it another chance at life and enjoying every minute
Offline   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Old 05-26-2012, 10:02 AM   #4 (permalink)
surprised
Diesel Starter
 
Join Date: Dec 2011
Location: Benson, Utah
Posts: 197
iTrader Score: 0 reviews

The intake manifold swap is no great shakes. You'll never feel any improvement from that alone.
The gearing is decent, I had the same with 29" tires and it was perfect. If you want to run big tires, you gotta gear up to compensate. 32" use 3.73:1, 35" use 4.10:1.
Offline   Reply With Quote Quick reply to this message
Old 05-26-2012, 10:07 AM   #5 (permalink)
jdemaris
Diesel Pro
 
Join Date: Oct 2006
Posts: 2,315
iTrader Score: 0 reviews

Quote:
Originally Posted by smokinblazer View Post
from a dead stop in dirt it barely turns the dirt over, not really spinning the tires, kinda like it lacks throttle response. .
From what you describe, I'd suspect low fuel delivery from a pump set too low. Can you make it blow a little black smoke when you stomp on it climbing a hill?

My 83 with a C-code engine (an intake). 3.08 axles and the TH400 can easily spin the tires on dirt with 31" tires. Your's with the super low first gear and 3.42 axles ought to do it even better. Are you sure you've got 1st gear? That super low 1st is one of the big assets of the 700R4/4L60.

My 1986 Blazer-mini-motorhome with a 4L60, 3.73 axles, 31" tires and a weight of 8600 pound also can easily spin the tires on dirt.

Years back I saw many 6.2s that got the fuel delivery turned down in an effort to gain fuel mileage. It would result low power, poor throttle response and no visible smoke when lugging.

Your fuel pump isn't' going to have anything to do with throttle response unless it's not working at all and "plugging" your fuel system. The injection pump can work with no fuel pump - but cannot work well with a "dead" fuel pump in the way and blocking fuel flow. If you ARE concerned about fuel delivery to the pump - you might want to check the screen-filter inside the fuel tank. I've had to unplug many that were clogged with diesel bacteria. As to Sea Foam? I don't believe it does a thing except empty wallets.
__________________
1982 K10 PU 6.2 diesel,1983 (two) Blazers 6.2 diesel, TH400, 1983 K5 Blazer with 6.2 diesel, 4sp man. OD trans. and Chalet pop-up camper body.
1986 K5 Blazer 6.2 diesel, 700R4 trans.- with Halmark pop-up camper body.
1987 V20 4WD Suburban 6.2 diesel, 1988 K5 Blazer 6.2 diesel, 700R4. 1989 GMC 3/4 ton, 4WD Suburban, 6.2 diesel, TH400 trans.
1991 Suburban 4WD 6.2 diesel 700R4 trans.
1981 (two of them) Chevy Chevette with 1.8 diesel and 5 sp. trans.
1985 Isuzu P'UP 4WD pickup with 2.2 diesel
1991 (Two of them) Volkswagen Jetta 1.6 diesel
1985 Ford F250 4WD ex-cab, longbed, 6.9 diesel
1994 Ford F250 4WD ex-cab, longbed, 7.3 IDI turbodiesel.
1983 Mercedes 300D five-cylinder turbo-diesel
1992 Dodge D200 4WD Cummins turbo-diesel, intercooled with 5 spd Gertrag
Offline   Reply With Quote Quick reply to this message
Old 05-26-2012, 11:14 AM   #6 (permalink)
smokinblazer
Clutch
 
smokinblazer's Avatar
 
Join Date: Feb 2012
Posts: 52
iTrader Score: 0 reviews

The mufflers are raptor brand, when I got the truck it had dual exhaust with echo tips, no mufflers. I had some put on to tone it down some. There was no noticable loss in power after I had them installed.

Yes I am positive I have first gear, just had transmission completely rebuilt about 3 months ago.

I do have the EGR intake, the vaccuum hose that runs to it is disconnected and blocked off. Haven't gotten to removing it yet.
__________________
89 K5 Blazer 6.2 Diesel
700r4
3.73 gears
33x12.50x15
Offline   Reply With Quote Quick reply to this message
Old 05-26-2012, 11:16 AM   #7 (permalink)
smokinblazer
Clutch
 
smokinblazer's Avatar
 
Join Date: Feb 2012
Posts: 52
iTrader Score: 0 reviews

Quote:
Originally Posted by jdemaris View Post
Can you make it blow a little black smoke when you stomp on it climbing a hill?
NO smoke. At night with headlights shining from a car behind me I can see the exhaust but in the daytime no visible smoke.
__________________
89 K5 Blazer 6.2 Diesel
700r4
3.73 gears
33x12.50x15
Offline   Reply With Quote Quick reply to this message
Old 05-26-2012, 11:50 AM   #8 (permalink)
legendman
Ex- 6BT Square Body Man
 
legendman's Avatar
 
Join Date: Aug 2008
Location: Oakdale, CT
Posts: 9,628
iTrader Score: 2 reviews

CT Smoke Member

Old School Oil Burners (Old SOBs) Member

Quote:
Originally Posted by smokinblazer View Post
The mufflers are raptor brand, when I got the truck it had dual exhaust with echo tips, no mufflers. I had some put on to tone it down some. There was no noticable loss in power after I had them installed.

Yes I am positive I have first gear, just had transmission completely rebuilt about 3 months ago.

I do have the EGR intake, the vaccuum hose that runs to it is disconnected and blocked off. Haven't gotten to removing it yet.

Wouldn't happen to be this kind would it?
I put a set of these on my K20, hope they aren't robbing to much power.
__________________
Quote:
Originally Posted by Diaric View Post
What your saying happened, should never be able to happen.
Quote:
Originally Posted by smackzed View Post
I put a chevrolet tailgate on my last truck and it started acting like a girl...love me, need me, want me pay attention to me. Took it off and put the GMC back on (fixed the latch) and it went back to being the same old dirty bastard it used to be
~ Bob
1987 K20 5.7 TBI 700r4 np208
1999 Chevrolet K2500 5.7L Auto
2006 Jetta TDI 5sp
2002 Golf TDi 4dr 5sp

Do yourself a favor and read the 6.2 Diesel Student Training Manual ... lots of good info...it's in PDF format located here >> PDF Manuals
Offline   Reply With Quote Quick reply to this message
Old 05-26-2012, 02:07 PM   #9 (permalink)
smokinblazer
Clutch
 
smokinblazer's Avatar
 
Join Date: Feb 2012
Posts: 52
iTrader Score: 0 reviews

Yep those are the ones. To me it did seem to run a little better after putting those on compared to straight piped. One day soon I hope to replace the full exhaust. Half seems to be the factory 1 7/8 pipe? from the manifolds half way back then steps up to 2 1/4. I want to replace all of it with 2 1/4 or 2 1/2 all the way and maybe some flowmasters. These evening I am going to a friends shop to swap out the axles for a set with 3.73 gears. If anyone knows what size freeze plug they used to block off the egr valve I would like to do that too while I am there. I will have to pick up the plug on the way, will be too late to go to the parts house by the time I pull the egr out. And when doing so is the vent system the only thing that will be left working off the vaccuum pump? I wanna do away with all that isnt needed with the egr system.
__________________
89 K5 Blazer 6.2 Diesel
700r4
3.73 gears
33x12.50x15

Last edited by smokinblazer; 05-26-2012 at 02:08 PM.
Offline   Reply With Quote Quick reply to this message
Old 05-26-2012, 06:12 PM   #10 (permalink)
jdemaris
Diesel Pro
 
Join Date: Oct 2006
Posts: 2,315
iTrader Score: 0 reviews

Quote:
Originally Posted by smokinblazer View Post
The mufflers are raptor brand, when I got the truck it had dual exhaust with echo tips, no mufflers. I had some put on to tone it down some. There was no noticable loss in power after I had them installed.

Yes I am positive I have first gear, just had transmission completely rebuilt about 3 months ago.

I do have the EGR intake, the vaccuum hose that runs to it is disconnected and blocked off. Haven't gotten to removing it yet.
Nothing in a exhaust system change is going to make you get that kind of negative response at the low end.

The EGR manifold won't make a noticeably difference either. You could yank it off and install a wide-open J-code manifold and a normal speeds not even notice the difference. In fact, I drove my 6.2 Blazer 120 miles on mountain roads with the intake almost 100% plugged and hardly noticed the difference in power. What I DID notice was I got 10 MPG instead of the usual 20 MPG and the engine ran extremely hot the entire trip. At first I thought I was getting senile and hard forgotten to fill the tank. But I then discovered a had a huge mouse nest inside the air intake. When I got to the mountain site where I was building a cabin - I didn't know what was going on. I really did think I'd forgotten to fill the tank before I left. As to the running hot - I didn't know. Once there, my little kid was playing around and stuck his arm up one of my 2 1/2" tailpipes and he was covered with soot. When I saw that - I knew something was wrong and pulled off the air cleaner. Found it plugged shut yet it still made good power. And - I had just checked it one week before for mice ! I cleaned it out and on the trip home it ran cool and got 21 MPG instead of 10 MPG.

You DO want to make sure your exhaust-manifold shutter is open on the driver's side. It's hooked to a vacuum pod. If your EGR is disconnected - that shutter needs to be wired open -or removed. If it's stuck - just make sure it's stuck open.

If you're sure you've got 1st gear I'd suspect low fuel delivery. I've seen it happen many times. somebody plays around and turns up the fuel. Then finds it's too much and turns it back down but goes too far. I'd turn the fuel up 1/16th of a turn and see if it responds. It might make a huge difference. If you like the first 1/16th, you can try it again until you start getting too much smoke under a load.







__________________
1982 K10 PU 6.2 diesel,1983 (two) Blazers 6.2 diesel, TH400, 1983 K5 Blazer with 6.2 diesel, 4sp man. OD trans. and Chalet pop-up camper body.
1986 K5 Blazer 6.2 diesel, 700R4 trans.- with Halmark pop-up camper body.
1987 V20 4WD Suburban 6.2 diesel, 1988 K5 Blazer 6.2 diesel, 700R4. 1989 GMC 3/4 ton, 4WD Suburban, 6.2 diesel, TH400 trans.
1991 Suburban 4WD 6.2 diesel 700R4 trans.
1981 (two of them) Chevy Chevette with 1.8 diesel and 5 sp. trans.
1985 Isuzu P'UP 4WD pickup with 2.2 diesel
1991 (Two of them) Volkswagen Jetta 1.6 diesel
1985 Ford F250 4WD ex-cab, longbed, 6.9 diesel
1994 Ford F250 4WD ex-cab, longbed, 7.3 IDI turbodiesel.
1983 Mercedes 300D five-cylinder turbo-diesel
1992 Dodge D200 4WD Cummins turbo-diesel, intercooled with 5 spd Gertrag
Offline   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Diesel Place : Chevrolet and GMC Diesel Truck Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

PLEASE READ! You must check your email inbox for the confirmation link to complete registration. Please check your spam box if you do not see the email in your inbox.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Insurance
Please select your insurance company (Optional)

Log-in


Thread Tools

Posting Rules
You may post new threads
You may 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


Similar Threads
Thread Thread Starter Forum Replies Last Post
lack of low end power silversootxpres 6.2L Diesel Engine 13 01-27-2010 11:23 AM
lack of power grh372 6.5L Diesel Engine 3 01-25-2009 10:54 AM
Lack of power and need some help! ttopformula 6.5L Diesel Engine 12 02-09-2008 11:31 AM
Lack of power blue duramax Duramax Second Generation: 2004.5-2005 (LLY) 2 03-04-2007 06:50 PM
Lack of Power? cacher1 Duramax First Generation: 2001-2004 (LB7) 10 08-15-2006 05:40 PM


All times are GMT -4. The time now is 06:00 PM.


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Shoutbox provided by vBShout v6.2.1 (Lite) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd. Runs best on HiVelocity Hosting.
© AutoGuide