Surging While letting off accelerator - Diesel Place : Chevrolet and GMC Diesel Truck Forums
 
Home Forum Market Place Garage Lounge (5) Tuning Library DTC Tool Register Vendors
Go Back   Diesel Place : Chevrolet and GMC Diesel Truck Forums > GM Diesel Engines > 6.5L Diesel Engine
Register FAQ Forum Rules My Replies My Threads Mark Forums Read Auto EscrowAuto LoansInsurance

6.5L Diesel Engine Discuss the 6.5 GM diesel engine & associated components.

DieselPlace.com is the premier Duramax Diesel Forum on the internet. Registered Users do not see the above ads.
Reply
 
LinkBack Thread Tools
Old 07-25-2011, 01:05 PM   #1 (permalink)
cabadiesel
Diesel Head
 
Join Date: Apr 2010
Location: Jacksonville Florida
Posts: 47
iTrader Score: 0 reviews

Surging While letting off accelerator

Hello All, I always come back to the site when in need and feel I never do my fair share of input when all is working well.

I have a situation with my Suburban and it is an "f" number. I am driving about 100 miles a day for the past week and this week compared to my 6 mile daily commute and have noticed that at first I thought my tires where way out of balance but would put the car in nuetral about 70mph and it would go away, If I accelerate hard it is real smooth. If I try to maintain or let off it bucks. Today when I exited the hiway and got to the bottom of the exit it bucks several times until I got bcak into the gas. I have the heath PMD under the bumper but am sceptical that it is the problem. No smoke, no hard starts, no acceleration problems, it actually is running great until I hold the trhottle contstant or let off gas pedal. I have original injectors and the IP was replaced at 50,000 miles by GM. I AM RELIGIOUS ABOUT CHANGING MY FUEL FILTER, do every 5000 miles and it could be bad fuel but still doesnt seem right, I have a huntch it is electrical. I am really busy and dont have time to run test on lift pump. any thought so when I do get stranded on side on I95 I can try to pin point better. HA

Thanks again for everyones help. The real engineers are on this forum, not in Detroit!
__________________
1999 Chevy Suburban 2x4
206,000 miles "F" 3.73
4' exhaust, remote PMD, boost gauge, KN filter
Offline  
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Old 07-25-2011, 04:29 PM   #2 (permalink)
DBLTRGR
Diesel Technician
 
DBLTRGR's Avatar
 
Join Date: Jun 2009
Posts: 334
iTrader Score: 0 reviews

That sounds a lot like my last two PMDs. After they were a couple of months old, if I took my foot off the pedal at highway speeds, the engine would buck. The difference on mine is that I had to take my foot off completely and that while it was bucking it was also belching black smoke. But I would try to swap your PMD with a spare to see if the problem goes away. If you don't have a spare tucked away in your truck then I highly recommend you get one. I've used mine twice in the last year.
__________________
DBLTRGR
Great Falls, MT

"Wise men still seek Him"

'99 Suburban, 200,000 miles on chassis with new Hiperformer long block (Optimizer and forged crank), 3.42 rear end, Remote PMD, Bilsteins, Bosch (India) injectors, 4 inch Diamond Eye exhaust with straight muffler and 2.5 inch cross-over.
Offline   Reply With Quote Quick reply to this message
Old 07-25-2011, 05:34 PM   #3 (permalink)
cheap9665
Diesel Technician
 
cheap9665's Avatar
 
Join Date: Feb 2009
Location: Albany, Wi
Posts: 471
iTrader Score: -1 reviews

sounds like my failed ip. try holding 2k rpms in park. thats what led me to an ip.
__________________
96 ext cab long box 4x4, 212k miles and counting, fresh trans rebuild and ip at 189k . pmd in front bumper, homemade 53cent turbomaster , bosch duraterms, moneyslave injectors, diamond eye straight pipe , draw tite remova-ball, 100 gallon diesel transfer tank, farm truck with ice cold air. . get about 18mpg on the interstate


06 chevy 3500 4X4 srw reg cab 496 BIG BLOCK . . . 34k miles, cognito 4-6 kit set at 5", stock torsion keys. 35 inch destination mts on pro comp wheels. Air lift bags in rear. used for fun and all my REAL towing thats too heavy for the 6.5


92 s10 2wd just my work beater getting lighter by the day
Offline   Reply With Quote Quick reply to this message
Old 07-25-2011, 09:19 PM   #4 (permalink)
cabadiesel
Diesel Head
 
Join Date: Apr 2010
Location: Jacksonville Florida
Posts: 47
iTrader Score: 0 reviews

Hold at 2k rpm?

When you hold at 2k rps it should not drop off at all correct? If so I guess I need a new iP. Any thoughts as to how much longer I should drive on it. I have two more weeks on 100 mile commutes!
__________________
1999 Chevy Suburban 2x4
206,000 miles "F" 3.73
4' exhaust, remote PMD, boost gauge, KN filter
Offline   Reply With Quote Quick reply to this message
Old 07-25-2011, 11:58 PM   #5 (permalink)
dreese_us
Diesel Technician
 
dreese_us's Avatar
 
Join Date: Dec 2010
Posts: 103
iTrader Score: 0 reviews

The two times that I had the surging problem, it was the lift pump. Once the the pump went bad, second time was the oil pressure sending unit. That goes bad, no juice to the lift pump. Truck will run without a lift pump, just puts a strain on the ip.

I don't remember black smoke or bucking.
Offline   Reply With Quote Quick reply to this message
Old 07-26-2011, 06:50 AM   #6 (permalink)
rbtaylor14
Diesel Technician
 
rbtaylor14's Avatar
 
Join Date: Jun 2010
Location: N.W Iowa
Posts: 160
iTrader Score: 0 reviews

Armed Forces Club Member

When was the last time you changed out your fuel filter? I would start there and then work into the other stuff. Also do you hear your lift pump when you turn the key on?
__________________
He promised "Change" Well he was right because that's all I have left.

Location: NW Iowa
1994 GMC Sierra 1500 Vin "S"
6.5L Turbo 192,500 miles
New 60g's Glow Plugs at 192,500
Relocated PMD #9 resistor
Custom Waste-gate bracket to increase boost
BD 3" Downpipe,Strait Pipe, Suspension upgraded to 1 ton, High Idle hooked to ECM
New Transmission at 189,000 miles built to be bullet proof.

Diagnostic Checklist <----------
The Official GM 6.5 TD "Newbie" FAQ <-----------
Edit Signature <----------------
Offline   Reply With Quote Quick reply to this message
Old 07-26-2011, 10:01 AM   #7 (permalink)
cheap9665
Diesel Technician
 
cheap9665's Avatar
 
Join Date: Feb 2009
Location: Albany, Wi
Posts: 471
iTrader Score: -1 reviews

Quote:
Originally Posted by cabadiesel View Post
When you hold at 2k rps it should not drop off at all correct? If so I guess I need a new iP. Any thoughts as to how much longer I should drive on it. I have two more weeks on 100 mile commutes!

mine would run up over 3500 when tryin this, from what i remember that meant the armature was letting excessive fuel past. . just my experience.
__________________
96 ext cab long box 4x4, 212k miles and counting, fresh trans rebuild and ip at 189k . pmd in front bumper, homemade 53cent turbomaster , bosch duraterms, moneyslave injectors, diamond eye straight pipe , draw tite remova-ball, 100 gallon diesel transfer tank, farm truck with ice cold air. . get about 18mpg on the interstate


06 chevy 3500 4X4 srw reg cab 496 BIG BLOCK . . . 34k miles, cognito 4-6 kit set at 5", stock torsion keys. 35 inch destination mts on pro comp wheels. Air lift bags in rear. used for fun and all my REAL towing thats too heavy for the 6.5


92 s10 2wd just my work beater getting lighter by the day
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:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



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
Engine smoke doesn't clear up until letting up on accelerator digital_EE 6.5L Diesel Engine 17 07-05-2011 07:56 PM
Surging when I take my foot off accelerator texasfirst 6.5L Diesel Engine 9 05-31-2010 09:36 AM
Mild surging whilst cold, quits surging when it warms up shafermike Duramax First Generation: 2001-2004 (LB7) 5 11-14-2007 09:46 PM
Letting the smoke out! Robotruck2500HD Duramax First Generation: 2001-2004 (LB7) 3 11-22-2006 11:55 AM
Letting the LLY Sit? NOTNSUV Duramax Second Generation: 2004.5-2005 (LLY) 8 06-26-2005 02:20 AM


All times are GMT -4. The time now is 12:37 AM.


Shoutbox provided by vBShout v6.2.1 (Lite) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd. Runs best on HiVelocity Hosting.
© AutoGuide

SEO by vBSEO 3.6.0