Low Idle and sudden stall

[grtescpa]

My trucks idle has been slowing down gradual in the past six months. It now idles at 600rpm. When you gun the throttle and let off quick the engine will stall. It use to do this when cold but now it does it all the time. A real pain when your trying to pull out into traffic and have to let up quick. The idle and stall is worse after a long 6 hour trailer pull. Anyone have any Idea as to what might be going bad?

 

[illflem]

Need to check your fuel pressure, I'll bet the the overflow valve is going. The spring in them seems to change with the temp of the fuel, that may be why you have more problems after working the truck.

 

[grtescpa]

Fuel press

Originally posted by illflem

Need to check your fuel pressure, I'll bet the the overflow valve is going. The spring in them seems to change with the temp of the fuel, that may be why you have more problems after working the truck.

That was fast! I just got done posting that 20 mins ago.

Where is the overflow valve located? Thanks for the quick responce!!

 

[illflem]

I may have been fast but that doesn't necessarily mean I'm right! The valve is located on the top front of your injection pump where the return line to the tank exits. It is actually the banjo bolt. Piers has the best deal going on new ones.

 

[Extreme1]

In the mean time...

Adjust your idle!!

 

[grtescpa]

fuel press

Originally posted by illflem

I may have been fast but that doesn't necessarily mean I'm right! The valve is located on the top front of your injection pump where the return line to the tank exits. It is actually the banjo bolt. Piers has the best deal going on new ones.

Right or wrong all answers are greatly appreciated!!!

 

[HomerDog]

I have the same prolem and have not found an answer. I set my idle and it is fine until I go on a long hard pull for several hours. The idle will slip 100-200 rpms. I've just been turning it up but would also like to figure out what's causing this. Truck is a 96.



Dave

 

[Andy Redmond]

Ck. fuel psi cold and hot



Has your fuel return line been changed?



Is your throttle cable in good shape? Shielded (new style) or do you have errant strands of the cable shredding and sticking in the cable housing causing erratic idle?



Is the fuel shut-off, not moving fully at idle or fully all the time?



good luck.

 

[carson6]

me too!! me too!

My truck idle's lower after a long pull too!!

 

[grtescpa]

Re: me too!! me too!

Originally posted by carson6

My truck idle's lower after a long pull too!!

I notice you have a 97. Did you ever check your killer dowl pin?

I think about mine all the time. I want to open up the cover very soon. I have 75k on mine. Been reading about many who have found the pin on its way out.

 

[grtescpa]

fuel line

Originally posted by Andy Redmond

Ck. fuel psi cold and hot



Has your fuel return line been changed?



Is your throttle cable in good shape? Shielded (new style) or do you have errant strands of the cable shredding and sticking in the cable housing causing erratic idle?



Is the fuel shut-off, not moving fully at idle or fully all the time?



good luck.

Same fuel line. I don't loose any power. I will take your advice and change the fuel line,check fuel press, overflow valve and solonoid lift at idle.

Thanks

 

[dseabaugh]

My truck has started doing the exact same thing. Let up on throttle quick and it dies. My Help is really getting annoyed. I'm used to it. Loaded after 50 to a 100 miles or so the idle seems less after every stop. maybe 500 rpms. on start-up it will run 750. Cummins majored pump about 30 k back and I would have thought the would have replaced the valve.

 

[Andy Redmond]

I also think the truck's governor is causing some of this grief. You are transitioning from the idle to medium springs, just off idle.



Try running an idle speed of what looks like 900 rpm on your tach. When a scanner is attached you may find your tach isn't very accurate below a 1000 rpm's. Usually they are dead on by 2000 etc. . Ie a true 750 may be closer to the 1000 mark than you think.



When setting idle have the a/c, blower motor and lights on. . when they are off you will idle a little higher, but here in Texas my a/c is always on!



I don't think you want to get it idling so fast that it requires both sneakers on the brake pedal to hold it still at a traffic light.



If you have a non- stock cam plate and afc, try enriching the pre-boost screw on the afc at 1/4 turn increments to see if a little more idle, off/idle fueling helps.



Often the 3k GSK, cures this, if the governor is a little touchy.





Of course our lucky friend illflem doesn't need a/c, as he has a nice summer climate!



Good luck

Andy

 

[Taz]

Originally posted by illflem

I may have been fast but that doesn't necessarily mean I'm right! The valve is located on the top front of your injection pump where the return line to the tank exits. It is actually the banjo bolt. Piers has the best deal going on new ones.

How much does Piers charge for those widgets?

 

[illflem]

Piers price is currently $55 USD, but he has had them on sale at times.

Originally posted by Andy Redmond

Of course our lucky friend illflem doesn't need a/c, as he has a nice summer climate!

Andy, you got that right, I'm still running fanless and I'm shooting for staying that way!

 

[Taz]

Originally posted by illflem

Piers price is currently $55 USD, but he has had them on sale at times.

Are these sales posted on the website? or a call only thing?

 

[illflem]

He usually has a section on his site with on sale items.