Won't idle and dies when letting off the pedal
02-08-2010, 10:52 AM
#1
Registered User
Thread Starter
Won't idle and dies when letting off the pedal
Central IL, not particularly cold right now (upper 20's). Running winter blend as well as conditioner in my tank. Been running perfectly the whole season but here is what is taking place today:
Fired up and drove my little girl to school. Fuel light came on as we were going over. Ran perfectly with no issues (about 8 miles on a highway). Once I got to town and had to let off the power, the truck died! Threw it in neutral, immediately fired up and ran to the school. Now it won't idle anymore without running rough and eventually dying. Drove immediately to the truck stop and filled up with winter blend (asked the clerk to be sure) and added conditioner, and made sure the water separator had been cleared in case of a slug of water. No leaks to be seen anywhere. While I was filling, I let it idle (still idling rough). Came out and the truck had died again. Fired right up and on my way. Drove 30 interstate miles to work, seems to run OK at speed. Same thing once I got to town, anytime I let off the pedal it would stumble and try to die unless I was feathering the pedal to keep it running.
What is going on here? I don't think it is the idle adjustment since I adjusted it quite sometime ago due to a low idle a few winters ago. Truck has performed flawlessly this whole season until today.
Fired up and drove my little girl to school. Fuel light came on as we were going over. Ran perfectly with no issues (about 8 miles on a highway). Once I got to town and had to let off the power, the truck died! Threw it in neutral, immediately fired up and ran to the school. Now it won't idle anymore without running rough and eventually dying. Drove immediately to the truck stop and filled up with winter blend (asked the clerk to be sure) and added conditioner, and made sure the water separator had been cleared in case of a slug of water. No leaks to be seen anywhere. While I was filling, I let it idle (still idling rough). Came out and the truck had died again. Fired right up and on my way. Drove 30 interstate miles to work, seems to run OK at speed. Same thing once I got to town, anytime I let off the pedal it would stumble and try to die unless I was feathering the pedal to keep it running.
What is going on here? I don't think it is the idle adjustment since I adjusted it quite sometime ago due to a low idle a few winters ago. Truck has performed flawlessly this whole season until today.
02-08-2010, 11:58 AM
#2
Administrator
How long has it been since you changed fuel filter or cleaned pre-filter?
I never like to let it get to the low fuel light, bigger chance of picking up garbage, past that, really shouldn't be anything else causing it.
We started seeing Bio here back in the summer, I haven't had any issues yet, but I always change filters before winter hits.
I never like to let it get to the low fuel light, bigger chance of picking up garbage, past that, really shouldn't be anything else causing it.
We started seeing Bio here back in the summer, I haven't had any issues yet, but I always change filters before winter hits.
02-08-2010, 02:18 PM
#3
Registered User
Thread Starter
Agreed on the fuel light. Sneaked up on me as I don't like running that close either.
Changed the fuel filter in early spring, and have never cleaned the pre-filter. Been on the to do list but never did it. Have the parts but not the time. I am hoping maybe some 911 additive will knock it out. If that doesn't, I will go with a new filter and go ahead with the pre-filter. Any tricks I need to know on servicing that?
Changed the fuel filter in early spring, and have never cleaned the pre-filter. Been on the to do list but never did it. Have the parts but not the time. I am hoping maybe some 911 additive will knock it out. If that doesn't, I will go with a new filter and go ahead with the pre-filter. Any tricks I need to know on servicing that?
02-08-2010, 04:04 PM
#5
Cummins Guru
If running ok at higher rpm without lack of power I would adjust the idle RPM first. The older 12 valves were notorious for idle stop screw wearing down and causing RPM's to drop off.
The high idle stop screw is factory sealed and cannot be adjusted. Low-speed idle can be adjusted.
1.Use an optical tachometer such as Snap-on No. MT139 or MTE (Cummins tool division) No. 3377462 to read the engine rpm.
2.Bring the engine to normal operating temperature.
3.Adjust the low idle speed at the low idle speed screw. The screw and locknut are located at the rear of the fuel injection pump Low Idle Speed Screw
4.Loosen the idle screw lock nut Low Idle Speed Screw Adjust idle screw to obtain specified rpm. Refer to IDLE SPEEDS - DIESEL ENGINE chart.
5.Tighten the locknut after adjustment (10mm wrench) Turn screw counter clockwise to raise RPM. After adjustment tighten lock nut and recheck since rpm may drop off a little after you tighten the lock nut up. Don't forget to tighten up the locknut or adjusting screw will rotate and idle rpm will drop off again on you. Good Luck!
IDLE SPEEDS - DIESEL ENGINE
LOW IDLE SPEED HIGH IDLE SPEED
With automatic transmission:* 750-800 RPM with transmission in drive and air conditioning on. Do not attempt to adjust high idle speed. High idle speed adjustment screw is factory sealed. Breaking seal will void injection pump warranty
With manual transmission:* 780 RPM with transmission in nuetral and air conditioning on.
* With engine at operating temperature. Refer to text for idle adjustment procedures
The high idle stop screw is factory sealed and cannot be adjusted. Low-speed idle can be adjusted.
1.Use an optical tachometer such as Snap-on No. MT139 or MTE (Cummins tool division) No. 3377462 to read the engine rpm.
2.Bring the engine to normal operating temperature.
3.Adjust the low idle speed at the low idle speed screw. The screw and locknut are located at the rear of the fuel injection pump Low Idle Speed Screw
4.Loosen the idle screw lock nut Low Idle Speed Screw Adjust idle screw to obtain specified rpm. Refer to IDLE SPEEDS - DIESEL ENGINE chart.
5.Tighten the locknut after adjustment (10mm wrench) Turn screw counter clockwise to raise RPM. After adjustment tighten lock nut and recheck since rpm may drop off a little after you tighten the lock nut up. Don't forget to tighten up the locknut or adjusting screw will rotate and idle rpm will drop off again on you. Good Luck!
IDLE SPEEDS - DIESEL ENGINE
LOW IDLE SPEED HIGH IDLE SPEED
With automatic transmission:* 750-800 RPM with transmission in drive and air conditioning on. Do not attempt to adjust high idle speed. High idle speed adjustment screw is factory sealed. Breaking seal will void injection pump warranty
With manual transmission:* 780 RPM with transmission in nuetral and air conditioning on.
* With engine at operating temperature. Refer to text for idle adjustment procedures
02-08-2010, 04:16 PM
#6
Cummins Guru
Here is a tech tip for incorrect idle speed adjustment concerns.
NO: 18-07-98
SUBJECT: Effects Of Incorrect Idle Speed
DATE: Feb. 27, 1998
NOTE: THIS INFORMATION APPLIES TO THE 5.9L CUMMINS MECHANICALLY INJECTED 12 VALVE DIESEL.
DISCUSSION:
Incorrect idle adjustments (either too high or low) may cause many different customer concerns. Following is a list of items that explain the condition/symptoms associated with incorrect idle settings along with component checks and specifications to set it properly.
RPM BELOW SPECIFICATION
Hard Starting/Stalling during cold engine operation.
Engine roughness at idle.
Reduction in the amount of vacuum available during idle from vacuum pump.
Delayed power steering assist when cold.
Excess seat shake and/or mirror vibration.
RPM ABOVE SPECIFICATION
Excess creep at stoplights/signs.
Vehicle does not reduce speed with foot off throttle.
Typically low idle speed is caused by a misadjusted low idle speed screw on the injection pump but high idle speeds can be caused by many items. The following list will help in diagnosing high idle concerns:
CAUSE REPAIR
Idle speed misadjusted Adjust low idle screw on injection pump
Misadjusted throttle/cruise control cable Adjust cables
Throttle linkage binding Clean and lubricate ball connections
Bent throttle rod Replace rod
Broken return springs Replace springs
Throttle/cruise control cable damaged Replace cable
The idle speed specifications for 1994 to 1998 models are 750 to 800 RPM. All idle speed measurements must be taken as follows:
Automatic Transmission In drive with A/C switched on
Manual Transmission In neutral with A/C switched on
When making idle speed adjustments, always use a DRB III, or an optical tachometer such as Cummins 3377462, Snap On MT139 or equivalent to read engine idle RPM.
NOTE: DO NOT USE THE TACHOMETER IN THE INSTRUMENT CLUSTER TO SET OR VERIFY IDLE SPEEDS. THIS TACHOMETER IS NOT ACCURATE FOR READING OR SETTING LOW RPM DURING IDLE CONDITIONS.
POLICY: Information Only
NO: 18-07-98
SUBJECT: Effects Of Incorrect Idle Speed
DATE: Feb. 27, 1998
NOTE: THIS INFORMATION APPLIES TO THE 5.9L CUMMINS MECHANICALLY INJECTED 12 VALVE DIESEL.
DISCUSSION:
Incorrect idle adjustments (either too high or low) may cause many different customer concerns. Following is a list of items that explain the condition/symptoms associated with incorrect idle settings along with component checks and specifications to set it properly.
RPM BELOW SPECIFICATION
Hard Starting/Stalling during cold engine operation.
Engine roughness at idle.
Reduction in the amount of vacuum available during idle from vacuum pump.
Delayed power steering assist when cold.
Excess seat shake and/or mirror vibration.
RPM ABOVE SPECIFICATION
Excess creep at stoplights/signs.
Vehicle does not reduce speed with foot off throttle.
Typically low idle speed is caused by a misadjusted low idle speed screw on the injection pump but high idle speeds can be caused by many items. The following list will help in diagnosing high idle concerns:
CAUSE REPAIR
Idle speed misadjusted Adjust low idle screw on injection pump
Misadjusted throttle/cruise control cable Adjust cables
Throttle linkage binding Clean and lubricate ball connections
Bent throttle rod Replace rod
Broken return springs Replace springs
Throttle/cruise control cable damaged Replace cable
The idle speed specifications for 1994 to 1998 models are 750 to 800 RPM. All idle speed measurements must be taken as follows:
Automatic Transmission In drive with A/C switched on
Manual Transmission In neutral with A/C switched on
When making idle speed adjustments, always use a DRB III, or an optical tachometer such as Cummins 3377462, Snap On MT139 or equivalent to read engine idle RPM.
NOTE: DO NOT USE THE TACHOMETER IN THE INSTRUMENT CLUSTER TO SET OR VERIFY IDLE SPEEDS. THIS TACHOMETER IS NOT ACCURATE FOR READING OR SETTING LOW RPM DURING IDLE CONDITIONS.
POLICY: Information Only
02-09-2010, 01:57 PM
#7
Registered User
Thread Starter
Let me add more info to this matter a day later.
Went out to the truck after work yesterday. VERY hard to start as though there was no fuel. Once it fired up, it ran perfectly. Ran several stops shutting off after fully warmed up, then drove the 30 miles home. Ran perfectly this entire time. Temperatures were not extreme at all. Keep in mind that I have winter-blend as well as a healthy shot of conditioner in the tank. I get within a quarter mile of the house and it dies! Starts right back up and is now running rough and wanting to die again just like in the morning. I had just driven 30 miles without problem!
Never got it to clear out, so I plugged it in for the night.
This morning, hard to start!!! Once again, like no fuel present.
After some grinding, fired up and idled perfectly. Tossed in a full bottle of 9-1-1 for good measure on top of the conditioner already in the tank. I let it sit idling for about 1/2 hour to get good and warm.
Not trusting it, I shut it off and left it home today.
Is this the filter? I am intending on changing it out tonight as long as I can find one handy.
Went out to the truck after work yesterday. VERY hard to start as though there was no fuel. Once it fired up, it ran perfectly. Ran several stops shutting off after fully warmed up, then drove the 30 miles home. Ran perfectly this entire time. Temperatures were not extreme at all. Keep in mind that I have winter-blend as well as a healthy shot of conditioner in the tank. I get within a quarter mile of the house and it dies! Starts right back up and is now running rough and wanting to die again just like in the morning. I had just driven 30 miles without problem!
Never got it to clear out, so I plugged it in for the night.
This morning, hard to start!!! Once again, like no fuel present.
After some grinding, fired up and idled perfectly. Tossed in a full bottle of 9-1-1 for good measure on top of the conditioner already in the tank. I let it sit idling for about 1/2 hour to get good and warm.
Not trusting it, I shut it off and left it home today.
Is this the filter? I am intending on changing it out tonight as long as I can find one handy.
Trending Topics
02-09-2010, 06:18 PM
#8
Registered User
Idle adjustment instructions> http://dodgeram.org/tech/dsl/adjustm...d_Gen-Idle.htm
Prefilter service> http://dodgeram.org/tech/dsl/filter/pre-filt_clean.htm
Prefilter service> http://dodgeram.org/tech/dsl/filter/pre-filt_clean.htm
02-10-2010, 12:14 PM
#9
Registered User
Thread Starter
Well here is the outcome. Used 9-1-1 in the tank and let it sit all day yesterday after letting it warm up in the morning. Went out this morning to start it up and it fired immediately. Drove it to work today with no issues at all. Temperatures remain the same outside.
Long story short, I think I got some bad fuel from a little station that didn't have enough volume rotation. Probably got summer blend of some form or bio that gelled easy?? I never go from my supplier, but I had to on that very last tank!
My idle is exactly where it should be from my previous adjustment so I am writing this whole issue off to a lesson learned. Only go to your normal reputable fuel supplier.
Thanks to all with your thoughts and suggestions. I hope to return the favor.
Long story short, I think I got some bad fuel from a little station that didn't have enough volume rotation. Probably got summer blend of some form or bio that gelled easy?? I never go from my supplier, but I had to on that very last tank!
My idle is exactly where it should be from my previous adjustment so I am writing this whole issue off to a lesson learned. Only go to your normal reputable fuel supplier.
Thanks to all with your thoughts and suggestions. I hope to return the favor.
02-10-2010, 08:38 PM
#10
Registered User
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One other thing to check when the weather warms is the fuel pick up tube in the tank. They crack, then when the fuel forms ice crystals on the pickup filter in the tank they start sucking air and do exactly as you describe.
Those rubber hoses in the tank should be changed when you change the hoses on top of the tank, and many people do not.
Those rubber hoses in the tank should be changed when you change the hoses on top of the tank, and many people do not.
02-10-2010, 09:45 PM
#11
Registered User
Thread Starter
darn it!!!! went out to the truck after work and it is doing it again. I will be replacing the filter and doing the pre-filter over the weekend. Must be bad fuel sitting somewhere!! going to look into replacing all the lines as well. darn it!!!!
02-11-2010, 09:23 AM
#12
Registered User
Thread Starter
5 degress this morning. Hard to start, ran for about 1 minute and hasn't run since. I located a new filter and pre-filter set in the shop and will be putting it in later today. Clearly I am having some sort of fuel gelling issue. I am going to research this site for some ideas on replacing all of the fuel lines as well. I figure I can eliminate a lot of things with new lines and filters. Dang!!
02-11-2010, 11:40 AM
#13
Administrator
How much fuel do you have left from that last tank?
I would get all of it out that I could, refill with known good fuel from your regular supplier, and then run it until you know for sure you have that fuel into the engine.
If I couldn't, I would put a couple of gallons of Gas in and drive it until teh fuel was gone.
I would get all of it out that I could, refill with known good fuel from your regular supplier, and then run it until you know for sure you have that fuel into the engine.
If I couldn't, I would put a couple of gallons of Gas in and drive it until teh fuel was gone.
02-11-2010, 12:45 PM
#14
Registered User
Thread Starter
This all started when I accidentally ran down to the light on a tank. almost as soon as the light came on, my trouble started. I immediately went to the local truckstop (reputable) and filled the tank. I have 90 miles on the new good fuel as well as the conditioner I put in and a botle of 9-1-1. I really thought that it would have flushed everything out by now.
Changing the filter and pre-filter should end this stupid situation. I am also looking into changing the lines.
Changing the filter and pre-filter should end this stupid situation. I am also looking into changing the lines.
02-11-2010, 04:50 PM
#15
Administrator
Ok, I guess I forgot that you hadn't changed the filter and pre-filter yet. Bet you got a slug of garbage and it is still stuck in the filter area.
Just for giggles, how many gallons did it take to fill from your low light? The 2 times that I had no choice it took 27-1/2 to 28 gallons to fill, meaning I have7-8 gallons left when my light comes on.
Just for giggles, how many gallons did it take to fill from your low light? The 2 times that I had no choice it took 27-1/2 to 28 gallons to fill, meaning I have7-8 gallons left when my light comes on.