Fluctuating manifold pressure - Diesel Truck Forum - TheDieselGarage.com
Thread Details Posted by Classic359, this thread has received 5 replies and been viewed 622 times.

 
LinkBack Thread Tools Display Modes
post #1 of 6 (permalink) Old 02-07-2018, 03:39 PM Thread Starter
Junior Member
 
Classic359's Avatar
 
Join Date: Feb 2018
Posts: 4
Points: 294
Thanks: 0
Thanked 0 Times in 0 Posts
Ok need help, got a 3ZJ manual pump 3406 cat. When I first bought Truck (Oct 2017) it would pull about 15 # manifold pressure and no smoke. After driving around 30 days, one day while coming home empty it all of a sudden started pulling 21-22# and trailing a little smoke. Had more power of course so I continued to watch the pyro and nothing over 750 so I continued driving it that way. Skip ahead to last week(Feb 2018), loaded headed west it all of sudden reverted back to only pulling 15# mp and trailing smoke stopped and felt gutless. Came home changed filters replaced transfer pump, checked fuel pressure (45-50+). AFRV plunger was removed to eliminate that, still doing same thing. Can start off leaving driveway and drive 5+ Miles and itís 21-22# then all of sudden while still pushing accelerator it falls off to 15# and seems to flatline. It has blew my mind why it would go back and forth doing this. Any tips???
Classic359 is offline  
Sponsored Links
Advertisement
 
post #2 of 6 (permalink) Old 02-08-2018, 10:17 PM
Junior Member
 
Jasong's Avatar
 
Join Date: Feb 2015
Location: Plant City Fl
Posts: 317
Points: 35,601
Thanks: 41
Thanked 26 Times in 25 Posts
Hmm. It's like it happens when it hits operating temp.
If you shut it down for a short while (not long enough to cool) what happens?
Jasong is offline  
post #3 of 6 (permalink) Old 02-09-2018, 03:47 PM Thread Starter
Junior Member
Threadstarter
 
Classic359's Avatar
 
Join Date: Feb 2018
Posts: 4
Points: 294
Thanks: 0
Thanked 0 Times in 0 Posts
Yes it seems like when it gets to the operating Temp I notice it also if I stop at a stop sign or get fuel At first it pulls good with high manifold pressure but as soon as I get Rolling good it governors back down
Classic359 is offline  
post #4 of 6 (permalink) Old 02-09-2018, 09:20 PM
w9l
Junior Member
 
w9l's Avatar
 
Join Date: Nov 2012
Location: Southwest Mo.
Posts: 515
Points: 59,101
Thanks: 237
Thanked 215 Times in 171 Posts
Garage
Well, if you have taken afr diaphragm out of the equation then ck timing advance and possibly governor flyweights are hanging up. I am assuming you do not have a gated turbo. Governor flyweights can do some strange things before they completely disembark. Ask me how I know. Also, check air charge cooling system when it is low and someone that knows more about air dryers than I do might be able to help you also.

Just me
w9l is offline  
post #5 of 6 (permalink) Old 02-09-2018, 10:18 PM Thread Starter
Junior Member
Threadstarter
 
Classic359's Avatar
 
Join Date: Feb 2018
Posts: 4
Points: 294
Thanks: 0
Thanked 0 Times in 0 Posts
I had planned on checking timing advance this weekend.
Classic359 is offline  
post #6 of 6 (permalink) Old 02-11-2018, 02:06 AM
Junior Member
 
Jasong's Avatar
 
Join Date: Feb 2015
Location: Plant City Fl
Posts: 317
Points: 35,601
Thanks: 41
Thanked 26 Times in 25 Posts
Quote:
Originally Posted by w9l View Post
Well, if you have taken afr diaphragm out of the equation then ck timing advance and possibly governor flyweights are hanging up. I am assuming you do not have a gated turbo. Governor flyweights can do some strange things before they completely disembark. Ask me how I know. Also, check air charge cooling system when it is low and someone that knows more about air dryers than I do might be able to help you also.
Interesting on the governor ⬆
That would explain things.
Jasong is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Diesel Truck Forum - TheDieselGarage.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

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:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
Speedometer fluctuating..... AaronF Medium and Heavy Duty 8 11-01-2013 01:54 AM
Fuel pressure & rail pressure gauges??? SS1156 5.9L Cummins (2003-2007.5) 9 07-23-2009 07:33 PM
manifold gauge pressure bcjag72 2008-2010 6.4L Engine Tuner Forum 8 06-23-2009 09:52 AM
Fluctuating/faltering engine speed Wrencher 6.7L Cummins (2007.5-2011) 9 10-26-2007 03:23 PM
Fluctuating Booost levels? DEERSNIPER 2003-2007 6.0L Power Stroke 3 02-28-2006 01:11 PM

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

 
For the best viewing experience please update your browser to Google Chrome