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My Boss's truck 1996 Dodge 1 ton diesel with a cummings engine, I don't know what size, but it is turbo charged.
I didn't drive it, but he says going down a steep hill it won't go past 60 mph, and stepping on it slows it down more.
This is NH, been pretty cold some snow changing to lots of rain, fog, and high humidity, plus it might be a woods rat moved in. It is cold and dark and I haven't popped the hood.
Other than icing, a nest, maybe a long shot jelled fuel, what could I be looking at?
Below 60mph he says the engine runs fine. he drove it 80 miles one way, where if it were ice i would think it would have melted off in a 3 hour buis meeting, and then he drove it 80 miles back.
Thxs for the link. Checking it out right now. I need that same truck for that same ride in the AM! I will pop the hood and have a look. I just changed the oil and all the filters last month.
Mac I have a 96' Cummins myself. I think you meant going "up" a steep hill no? I'm gathering that the power tops out prematurely? First of all in this cold weather you should be running PowerService Diesel Supplement with Cetane boost its the WHITE bottle NOT SILVER. This will take care of gelling and make the engine run like silk. I run it in my main tank in frigid temperatures and use two stroke oil otherwise.
I would immediately change the fuel filter. If that does nothing for him there is something called an overflow valve, it basically governs the fuel pressure for the feed into the injection pump. I just replaced my valve ($25) at 180k and pressure shot up to normal range and the truck really woke up. The valve's internal spring weakens over time and causes fuel pressure to drop.
Replace the fuel filter and then get back to me and I can tell you how to do the valve, its a 10 minute job. Heres a couple part numbers for the filter:
Fleetguard: FS1253
Baldwin: BF1233
Additionally here is the source of all my Cummins information technical and non:
Thxs Lux, I will swap out another filter in case. It's only a month old and we have smaller vehicals for every day use. The fuel is fresher, unless it got water in it from the pumps.
Air temps here have been down as low as -1 below, but most of the time in the mid 20's F. I don't do centigrade/celsius.
Will check out links.
Plaidmom, you link, unless I am wrong wants a 35 dollar per year subscription. I for sure can't find any registery button, to simply log in. One old magazine mentions 50% loss of power, but the mag is for sale. This isn't my truck, so no dice on any 35 bucks for a question.
Probably with no book at all i can figure this out, but not in clouded over darker than hell cold night.
I did that last night on my own dam car, finding vac leaks and the fact the new valve cover gasket was the wrong one Grrrrrrrr
The problem being a engine breather hose has to be pulled from a tight spot and is a sonnybeach to reinstall 85 volvo turbo at the flame trap, if anyone knows where that jewel of *****-earring lives.
Mac if the filter is only a month old then its probably not that. Here is an ebay link to the overflow valve. I did a buy-it-now on the item and Larry had the valve at my doorstep in literally 2 days:
I'm willing to bet this is the problem. If not, it still needs to be replaced anyways and it WILL make a difference.
P.S. One thing I forgot! There is a fuel pre-heater before the lift pump. There is a screen in it and they frequently clog. I forgot about this because it is bypassed on my truck... its something that every DIY 12 valve owner bypasses mainly because it is a pointless device and does not help at heating the fuel. It only gets clogged and causes issues. If this is not bypassed on his truck then take it apart and clean the screen... you might find your problem there. Here is a link to a fuel system write up, glance through it and you will see everything i'm talking about:
Plaidmom, you link, unless I am wrong wants a 35 dollar per year subscription. I for sure can't find any registery button, to simply log in. One old magazine mentions 50% loss of power, but the mag is for sale. This isn't my truck, so no dice on any 35 bucks for a question.
Probably with no book at all i can figure this out, but not in clouded over .
I was ~hoping~ you might find an answer on the free forums:
I can't register and can only read the OP 1st post, no replies. I can read at least one post, where there is a similar question, but can't search, can read and can't post, since I can't register.
In the AM I will look these items over as i swap another filter in. I think you are registered and posted this link in away I can see, but i am not sure it's legal.
I'd change the fuel filter (again)
Where is he getting his fuel at?
Is it old, does he get it out of a storage tank or at a station?
If he has straight #2 in the tank in might be getting cold enough for it to start to gel.
(maybe)if it's been a while sence he filled up he still could be running summer fuel as winter fuel is blend of #2 
Change the filter and dump in something like power service in the white bottle in to the tank.
The air filter is a folded paper element with a foam pre filter. The air goes thry the pre filter first. It is spotless. I can not 'see' any failure in the intake track, all the rubber boots are intact.
I pulled the cat off, and test drove it, that added power from 0 to 60, and I can get the rig to 62 mph. The cat is partly clogged. The lowend is improved alot.
We get the fuel at a local Citgo, there is about 3/4 tank now. I am going to intall a new fuel filter next, after a little coffee. The fuel is recent, so unless it is fubarred fuel it should be a winter blend.
LUX, can you copy and paste the thread name / title ? No dice seeing that page with the link.
Same thing happens 'no page found' for this artical Joe G's fuel system writeup in Beginners Thread (read first) grrrrr I need that truck right now to drive 160 miles and pick up a promised machine today! it weighs a ton, nothing else here can do it. Ahhhhhhhh
Last edited by Mac_Muz; 12-15-2010 at 11:56 AM..
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85 volvo turbo at the flame trap, if anyone knows where that jewel of *****-earring lives.
