1994-1998 12V Idle Adjustment - Diesel Bombers

94-98 12V Cummins 5.9L P7100 Tech Talk '94-'98 5.9L Cummins 12-Valve P-9100 Tech Articles

LinkBack Thread Tools Search this Thread
Old 11-23-2007, 11:21 PM
Thread Starter
Join Date: Mar 2007
Location: Perry Co. Ohio
Posts: 29,849
Thanked 3,296 Times in 1,639 Posts
Default 1994-1998 12V Idle Adjustment

Adjusting the idle speed on the diesel engine is not difficult. The adjustment is located on the driver side of the injector pump near the rear of the pump. You will need a 10 mm wrench.
Correct speed is:
  • 1994-1998 with AT - in drive with AC on 750 -800 RPM
  • 1994-1998 with manual in neutral with AC on 750-800 RPM
  • NOTE: These speeds may cause stalling when the engine is cold. If this is a problem for you, bump the idle speed to 900 RPM.
Idle Speed Adjustment
There are several ways to reach the idle adjustment.
  1. Go in from the front of the truck - Lay over on the radiator and snake the right arm back and down to the adjustment.
  2. From a short stepladder beside the driver side tire - Reach down from behind the injector pump to the adjustment.
  3. Stand on 5-gallon bucket by the drivers wheel, lean in under the hood and put the back of your head against the hood insulation - reach your right hand under the brake master AND under the ABS lines to the back of the pump. From any of the positions above, you can easily feel a vertical bolt with the extra threads on the bottom. The locknut is on the bolt threads below the boss on the pump housing.
An open end wrench will usually loosen the locknut, it is difficult to get a box end wrench to fit onto the locknut.
  • Loosen the 10 mm Locknut on the low idle adjusting screw at the rear of the injector pump.
  • Take the left hand and gently push the linkage rearward to take the pressure off and with the right hand
    • turn the idle screw counter clockwise (up) to increase idle speed
    • turn the idle screw clockwise (down) to decrease idle speed
  • Look at the RPM and repeat to get what you want.
  • Tighten the 10 mm locknut when the idle speed is correct.

Last edited by Dr. Evil; 11-24-2007 at 01:50 AM.
Old 11-23-2007, 11:22 PM
Thread Starter
Join Date: Mar 2007
Location: Perry Co. Ohio
Posts: 29,849
Thanked 3,296 Times in 1,639 Posts

Another Way...

> How do I adjust the idle speed on my Ram diesel? The idle speed seems too high.
First, trace the accelerator linkage to the connection on the fuel pump. With the ENGINE OFF have someone floor the accelerator and watch the fuel arm move. The best position I can describe is that it is under and to the left of the fuel filter on the rear of the fuel pump. A Flashlight and a mechanics telescoping inspection mirror would best serve as your visual aids as there is little room to move around and get a view of this area.
Once you have located the fuel arm the idle adjustment bolt is where the fuel arm normally rests on. It is easier to see and adjust if you have someone hold the accelerator down. The 10mm bolt that the fuel arm rests on threads into the bracket that you see and has a 10mm lock nut on the underside of the bolt. Loosen the lock nut and adjust the bolt on top in for a lower idle speed and out to raise the idle. I have found that the truck works well with the idle set at 750 rpms and this is the first white line below the 1000 rpm mark on the tach. Start the engine and observe the idle speed and put the truck in gear (if automatic) and turn the AC on. If the truck doesn't try to stall then you are set. Make sure that you tighten the locknut good when you get your desired idle speed.
An observation I have made. With the idle speed set below the factory set point it is easier to start the truck when you gently put some slight pressure on the accelerator while cranking the engine. Applying to much pedal will generate a a real smoke cloud so its an experimental thing that you need adjust by feel until you get it just right.
Old 11-24-2007, 08:29 AM
Diesel Fan
Join Date: Oct 2007
Location: Portsmouth Va
Posts: 61
Thanked 5 Times in 5 Posts

I concur with flooring the accelerator. It makes it easier to see what you are doing. Thanks for the tips, greatly appreciated.
Old 05-17-2008, 12:53 PM
Join Date: May 2008
Posts: 1
Thanks: 0
Thanked 0 Times in 0 Posts

I followed your instructions and it was right on the money. I set mine at 900 rpm automatic with AC on. Thank you for the instructions.
Old 09-02-2009, 07:18 PM
Diesel Fan
Join Date: May 2008
Location: C.O.springs
Posts: 21
Thanks: 0
Thanked 0 Times in 0 Posts

thanks from me too i had the same problem went out did it just now sounds great we will see tomorrow morning already did fuel filter and found leak in small hose at primer pump?replaced.
Old 09-03-2009, 10:34 PM
bowtech's Avatar
Diesel Bomber
Join Date: Mar 2009
Location: Arizona
Posts: 1,007
Thanked 11 Times in 10 Posts

i need to set mine in drive no ac at all its just under 500 rpm

Related Topics
Thread Thread Starter Forum Replies Last Post
cummins 1994 with 1998 12v engine problem! jeremy01995 12 Valve 2nd Gen Dodge Cummins 94-98 1 09-14-2015 06:34 PM
1994 6.5 blazer touchy throttle, erratic idle in park only Jake202 Chevy/GMC 6.2L and 6.5L 7 06-21-2015 09:42 PM
1994 12v sputtering help cummins Pride 12 Valve 2nd Gen Dodge Cummins 94-98 0 04-18-2015 11:54 AM
1998 Dodge QUAD CAB 12V Long Bed (Seattle) torino73 12 Valve 2nd Gen Dodge Cummins 94-98 0 04-14-2015 11:15 PM

Thread Tools Search this Thread
Search this Thread:

Advanced Search

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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

All times are GMT -5. The time now is 12:01 PM.

© 2018 MH Sub I, LLC dba Internet Brands
We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.