hot idle chugging

[cmann250]

This is good, I guess. I've never had a miss, but I do have a rough idle every time after an hour at ~2200 rpm (70mph).

Phew it's some other strange thing

[ellis93]

Thats how it started

[RCCUMMINS89]

Yep, it starts as a random low idle...especially after it's been worked hard. I'm currently at the point that I gave it a higher idle so that it's not so noticeable when it gets hot. My dad's completely stock truck is starting to do it too.

I'm wondering if a lot of us are noticing the lack of lubrication in the new diesel fuel. That's one way to get us older trucks off the road. "epa" the fuel to the point that it ruins our injection pumps.

[1992gen1_fan]

When mine acts up the rpm changes at idle are barely noticable but the "miss" is. Its almost similar to a lope, the engine is also louder usually. Next time it does it I'll pour some cold water on the pump and see what it does. I sure hope the pump is'nt going out again. It has less than 50k miles on it.

[ellis93]

Dude at my pump shop said thats a no no,said it'll seize up the h&r

[RCCUMMINS89]

Well.........depends on what pump shop you ask. LOL.... no, don't pour ice cold water on it

[cmann250]

Yep, it starts as a random low idle...especially after it's been worked hard. I'm currently at the point that I gave it a higher idle so that it's not so noticeable when it gets hot. My dad's completely stock truck is starting to do it too.

My idle has always been low, so I don't think it's the pump. Yet. I don't like my truck whistling away at 1000 rpm warming up in the driveway. It's a tightly wound automatic vs. manual thing too.

[1992gen1_fan]

Yea definatly would not pour ice water on it lol, that would ruin something going from hot to ice cold that fast lol. I'd just use tap water or even room temp water. I would'nt completly soak it all at once, do it slow.

[RCCUMMINS89]

Yep, it starts as a random low idle...especially after it's been worked hard. I'm currently at the point that I gave it a higher idle so that it's not so noticeable when it gets hot. My dad's completely stock truck is starting to do it too.

My idle has always been low, so I don't think it's the pump. Yet. I don't like my truck whistling away at 1000 rpm warming up in the driveway. It's a tightly wound automatic vs. manual thing too.

Ya, I run a high idle because it makes take offs incredibly more smooth with a dual disc.

[kwrank]

so i'm in the same boat (truck, pump, whatever)--problem developed gradually, now after 20 mins the idle drops to where the oil light comes on. stabbing the throttle doesn't help much, but slipping it out of gear (auto), the idle will jump right back up. have increased cold idle speed, checked throttle index etc...cold water didn't help. is this a slam dunk diagnosis, or is there a possible gremlin or two i can chase down before going off to pump city? runs fine other than this, a bit smoky down low. 90k on a quality rebuild, i would agree that the fuel is not keeping things lubricated, even with semi regular additive use.

[mhuppertz]

How is your fuel pressure? Maybe your lift pump is unhappy.
Cooling your IP should make it run better if that is what the issue is.

[kwrank]

don't have fuel pressure gauge, was thinking it would be worth it even to set up a temporary to help with this problem. piston lift pump has 15k on it, only a gauge will tell for sure, eh? have been wondering about the fuel tank, as there have been instances when the idle drops way down while backing down a steep slope while out after firewood, or even on my driveway, which is relatively steep. worth dropping the tank while waiting for fuel pressure parts to arrive?

[RCCUMMINS89]

How is your fuel pressure? Maybe your lift pump is unhappy.
Cooling your IP should make it run better if that is what the issue is.

Hey......mhuppertz..........check your pms

[kwrank]

bumping this back up because its summertime, and suddenly i need the truck a lot more, and am (sort of) ready to deal with whatever problem this is--symptoms same, cooling pump doesn't help, idle jumps right back if i put it in park or neutral. never got fuel pressure gauge, just wanting to be sure i'm on right track before i pull pump. any thoughts or experiences out there? thanks k

[RCCUMMINS89]

How far is your rpms actually dropping? I mean, it'll drop when you're in gear...