Low fuel mileage and rough idle
 

Like the title says guys I seem to have a couple of problems here. When the truck is first started in the morning the truck seems to idle fine an the rpms stay preaty well steddy, but after its up to operating temp it seems to have a slight a miss or a hiccup to it:argh: and the fuel mileage has just started to start to go down hill for some reason. Oh an also when the truck has set for say a day an when I go to start it it seems to have to crank longer than usual, but after its been run it doesnt have the problem anymore. For the rough Idle Ive check for codes and have none that pretains to the vp an I just replaced the vp bout 5 months ago with one from Industrial Injection and it sees a constant 14-17 psi fuel pressure from the airdog. Ive also replaced the apps sensor too. So my question is what would be causing this thing to have a rough idle? Could it be the injectors needing pop pressure adjusted, air in the fuel lines, fuel lines sucking air somewhere, maybe a sensor, or possibly the overflow valve at the vp?? Im to the point that Im bout ready to set a 20lb box of dynamite under it an watch it go boom. So any help or suggestions would greatly be appreciated.

Thanks Andrew

Sounds like injector issue. You can crack your fuel lines to check for air. Might need to pull the injectors and get them tested like you said. Id ask when was the last time you got your valves adjusted but it sounds more like an injector problem. Dont use dynamite. Everything can be fixed:c:

Yeah I adjusted the valves probably 3 weeks ago. I set them at .008 intake and.018 exhaust.

Is your truck smoking more then normal?

No not really just when I have the Smarty turned up, but my cousin told me that he noticed it blew just alittle bit of blue smoke. Which is why I was wondering bout the injectors maybe one isnt seated properly an is letting oil come down the side of the injector.

sounds like you have an injector missfire. my truck does the same thing, and thats what i narrowed it down to.

Ok so I just went an bleed my fuel injectors all except for no. 2 and the truck seem to run preaty smooth for the most part. When it got up to around 170 degrees it started to have the same ol miss/hiccup to it as before. So Im leaning to maybe a sticky injector/injector missfire. Anyone else have any suggestions??? Thanks again for the info and help guys:tu:

So Ive been thinking an was just wondering but when u bleed the injectors are they supposed to have alittle foam coming out or just pure fuel with no foam?

yea your gonna have some bubbling since your gonna have air in the lines as long as you have fuel to 1,3,4 it should start itll be ruff for a little bit but it should smooth out.

So just alittle update today when I was sitting in the parking lot I raised the rpms slowly and noticed that the truck had some vibration to it. Now I know the mighty Cummins shakes and any diesel for that fact but this was not motor vibration. It seemed to happen between 1500-1800 rpms give or take, but when I revved it to 2000 an above it smoothed out. What does this sound like to yall? Maybe a stuck injector, air in the lines, or something else? I stopped by the Kenworth on the way home and ordered the o-rings for the connector tubes, o-rings for the injectors, and the copper washer for the injector. Do yall think this will help or should I look into something else?? Again the vp's been replaced bout 5 months ago and no codes pretaining to vp an it's recieving anywhere from 15-18 psi from the airdog. Im also considering replacing the fuel lines to an fromt the airdog also. Again thanks for all the info and help guys:tu: