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Discussion Starter #1
this has been happening for a long time, but im getting really tired of it. just driving around, the truck runs fine. but if i go out and run hard on the highway, or tow my boat( which is only a 17 footer), when i come to a stop in gear, the oil pressure flatlines, and the engine starts to stumble and die. it only takes a tiny bit of pressure on the go pedal to keep it running, but that is a pain while mauvering a trailer. if i let it idle in neutral for a good 45 seconds to a minute, then go to move it again it will idle fine. this also happens more frequently as the air temperature exceedes 85-90 f.

any ideas?
 

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Discussion Starter #2
my dart does the same thing under similar circumstances, which i find very odd
 

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I guess bad injection pump, on top of a finicky and unrelated oil pressure sender.
 

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I how many miles do you have on the truck. I could be a weak oil pump. The thinner the oil the harder it is to pump.
 
G

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Jake is close. Very Close!

Could be bearing damage or a bad pump or the oil you are using.

The oil is at it's hottest when you are doing highway, so it's thinner. That makes it harder for the pump to maintain pressure for lack of resistance. Or the oil you are using is not correct.

What oil are you using? Rotella is one of the best. You find that in all the truck stops too.

Click on my signature and join our forum. We can talk about the Dart there. I'm a big Mopar guy. And pretty good at troubleshooting.
 

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Sounds like IP. The oil pressure flutters due to the lowered idle and engine dying. Throw a mechanical guage on there and turn the idle or full fuel screw in a bit. A slightly higher idle won't hurt anything at all. Besides, you may as well get all the life out of the first pump before you swap them.
 

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Discussion Starter #7
she doesnt have 130k on her yet. what part could have worn out that quickly, since this has happend since i got it? i agree it could be the engine oil, it is not the best stuff around, and it is due for a change(back too rotella). the thing is, its not consistent. it will usually run the highway all day and be fine. its only when its really hot out. To be honest ive never worked hard in the snow and cold, so im not sure aboout that.

could it be the tranny fluid? im 99% sure it has dexron 5 (the fish oil stuff) in it. im changing it in the next week or two, along with the filter.
 
G

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Check to be sure the cooling system has been maintained. You may have some crap in there that needs to be flushed.

Do the oil change to Rotella if that's not what is in there. That could be all it is.

When bearings get worn, the oil pressure will drop as it gets hotter. But now that you have said more info, I suspect you need to go to a better oil.

I never drove my trucks that high in mileage. I always move into the newer models because they have been usually better. But I have seen the oil pressure drop a tad in one of my 12 valves after 90K. But no where near what you are talking about.

Your low oil pressure cut off is what is shutting it down I think.
 

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Discussion Starter #9
i was experimenting with different brands of oil, this one failed, so it seems. ill change it tommarow, since im going to the store anyway. i had rotella in during the winter while i was plowing, and never a hitch.

the cooling system is passible but not great. i have flushed it twice with no noticeible differences. it has never overheated on me.

are these trucks equipped with a low oil pressure shutoff?
 

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Did you try turning up the low idle? mine is higher than spec at 850 and runs smooth. My 97 cummins did the same thing ( I know it has a diff injection pump ). It would die sometimes in gear if you let right off the throttle. Turned up idle and its fine.
 

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Discussion Starter #11
richie, i have thought about it. im gonna try the new oil first, then change the idle.

i see lots of high speed driving in the future!


thanks for the help guys!!!
 

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Check to be sure the cooling system has been maintained. You may have some crap in there that needs to be flushed.

Do the oil change to Rotella if that's not what is in there. That could be all it is.

When bearings get worn, the oil pressure will drop as it gets hotter. But now that you have said more info, I suspect you need to go to a better oil.

I never drove my trucks that high in mileage. I always move into the newer models because they have been usually better. But I have seen the oil pressure drop a tad in one of my 12 valves after 90K. But no where near what you are talking about.

Your low oil pressure cut off is what is shutting it down I think.
It doesn't matter how much crap is in your cooling system, if it's not overheating, it's not causing a problem.
There is no low oil pressure shutoff on these engines. The low oil pressure is not a cause, it's a symptom. There's nothing wrong with your oil, oil pressure, transmission fluid, tire pressure, windshield washer fluid or any of the myriad of other maintenance items. Your oil pressure is dropping because as the engine is stalling out the engine rpm is dropping below the speed it needs to sustain normal operating pressure. Your problem is absolutely related to fuel delivery, most likely an issue within the injection pump. To be save and sure I would change the fuel filters, but I doubt that will correct anything. Assuming you have good fuel. The IP is likely on it's way out. As was posted earlier, you can extend it's life and improve the driveability for a while by increasing the idle speed by either the idle stop screw or the fuel screw. In the meantime, start banking your penny's for the o'haul of the I(njection) P(ump).
Steve g
 

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Fyi...

I never drove my trucks that high in mileage.
FYI, these are the 1st Gen forums where the trucks routinely see service out to 300k miles with minimal routine maintenance, half a milion is not uncommon, and a milllion is achieveable in a truck that has been well maintained.

I'd venture to guess that since you haven't gone beyond 130k, your prodigious troubleshooting skills have yet to scratch the surface. :rof
 

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Discussion Starter #14
In the meantime, start banking your penny's for the o'haul of the I(njection) P(ump). /Q

steve g: i know what an IP is. i know its a fuel problem. the filters are new. I know. i was taking advice and keeping my options open, since the truck will be scrapped if the ip goes.


what part of the injector pump could get shakey at really high temps, but work fine other times? thats what i dont know.
 

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Not being an injection pump technician I can't tell you with certainty. What I suspect it to be is that the pump is a piston pump with extremely close tolerances in the bores. As the pump wears and these clearances increase the change in viscosity of the fuel as it heats up and the changes in clearances as the pump heats up reduces the effectiveness (volume) of the pump stroke.

BTW, I know your pain. Mine is doing the same thing, doesn't stall often, but idle is significantly reuced when hot.

Interesting aside, I heard from one of the Ag service reps that the pump clearances on the new engines are so tight and the new ultra low sulphur fuels so lacking in lubricity that they have actually had cases of IP's seizing up. The pump manufacturers are now saying they are not going to warrant pumps damaged by poor quality fuel. They tell us to warn our customers to use fuel additives if they want to retain their warranty.
Steve g
 

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My trucks do the same. They always have. One pump is a replacement and the other passed 320,000 miles.
 

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My truck has always dropped idle speed on sudden deceleration. (Truck in neutral, moving forward and hit brakes) And always increased idle speed doing the same thing in reverse. I've always ASSUMED it was something in the IP that the inertia was effecting.
 

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Idling is a an Art

The way it idles can tell you alot about the condition of your engine. Injectors getting marginal, IP issues, valvettrain, etc, etc.
 

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I'd check lift pump output pressure. If it isnt up to snuff, it can cause your IP to have to suck a vacuum to get fuel, instead of getting pressurized fuel at the inlet.

Just because it is low mileage doesnt mean the fuel system is in tip top shape. Of the 8 or so 1stGens I've had the one that sucked the most fuel was a cream puff- light loads, lots of idling, etc. At 130K, the injectors were shot. The one that ran the best was a fleet truck that had a trailer hooked to it 90% of the time- had 5 of 6 injectors popping like new at 260K.

Daniel
 

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Discussion Starter #20
i replaced the lift pump last summer, the old one had cracked right through.

ive been wondering about the injectors, because the engine seems louder that it used to be. it has a clacking noise in the top end. not a valve train noise, but a combustion rap. i was testing it out on the highway the other day, and blew my first (noticed ) cloud of smoke! not a big one, but enough. the truck is pulling hard and stong, for what its worth.
i drove her on a two way drive of about 14 miles each way the other day, as a test. the trip out, i stayed exactly at 55mph, and had no problem idleing at stoplights. the trip home i cruised at 55 again, but with some bursts to 60-62, and it pulled fine, but lagged off at idle. its never stalled, but it does get shakey.
 
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