Adam8361

Hi everybody,
I have an 04.5 Commons Rail and it has been getting poor mileage. Also had a slight stutter at startup but always started right up. It also sounds terrible when it idles up to 1000 rpms, it surges up and down but no change in rpms on the tac. Idle is a little rough at cold startup but worse after it warms up. Tried a few things: Check cascade valve and replace FCA on injector pump, check for bared wires, change fuel filter (again), clean air filter, and had fuel pressure tested at local shop. He thought maybe I had a slow leaking injector so I put a new set in. Was no noticeable smoke or fuel in oil. Injectors fixed the slight stutter at startup but still getting bad mileage and surging at high idle. I've had the truck for over three years and it is not getting near the mileage it used to...down about 4 mpg's. No codes, everything is normal on scan tool.
Any ideas?

Thanks,
Adam

DBLR

Have you worked the engine hard lately or used injector additives? It may be a good idea to hook to a 5K trailer and drive it for 3-4 hours to help burn off the carbon an at the same time to use some Howes meaner cleaner to help clean up the inside of the injectors. I see your in MN are you using winterized fuel? As for lower mpg its normal in the winter and also MN upped the Bio content to 5% from 2% so that may also cause lower fuel mileage.

Adam8361

I use the truck periodically to haul 35' livestock trailer which should work it enough, I do drive it pretty nice though. I've also been running #2 diesel with Power Service winter additive/cleaner. I know the mileage goes down a little in the winter but it is worse than previous winters. Problem started late fall and mileage was bad then too. I replaced the injectors with rebuilts so they should be clean. Thanks for the heads up on the bio-fuel. A diesel shop thinks I may have a loose injector supply tube...taking it in Tuesday to let him have a look at it.

Thanks alot for the input! If you have any other ideas I would appreciate it.

DBLR

Hauling a 35 ft trailer should be more then enough if you drive it at least one or more hours once per month. Did you change over to new winter traction or more aggressive tires? I did this year and noticed lower mpg compared to last year with A/S tires, that and the fuel we get is now mixed 70/30 (70% #2 & 30% #1 diesel mix) instead of Arctic treated fuel that for some reason they claim will cause Bio to glob up in cold temps so we now suffer with a loss of 1.5 mpg.

solidwhiteline

Adam: The ingredients of diesel fuel have been continually changing. Here they have started adding animal fat to the mix in addition to grain, veggie stuff.
When you have your truck parked, the fuel is not being agitated. What starts happening with diesel, unlike gasoline (which has different issues), is water drops to the bottom of fuel tank because it's heavier. Diesel fuel rides above it.
In between is a pocket of air....This is where mould, bacteria, start growing.
You see, when diesel fuel breaks down its components start going out of solution. The fuel line, injectors start to clog.
What is needed is a dose of a fuel catalyst that prevents the fuel from breaking down..even if it sits idle in storage for 5 months. It needs to contain a fungicide, a bacteria killer and an evaporator (non-alcohol base).
The catalyst changes the fuel so it combusts fully in the combustion chamber...not in the exhaust pipe. The only product I've encountered that performs so perfectly is EPA listed.
Oh - it also allows an instant start-up next day down to minus 45 degree F.
It's manufactured by Shellbourne Fuels.
Hope this helps.

Adam8361

Thanks for the info everybody. I think I might know what the problem is now. I had just left home and was going up a hill and the truck began to slow down and kind of coughed a couple times. I stopped and it was idling normal. I turned around to go home and tried to accelerate easy but did it again once it got up to 1500 rpms. I limped it into the garage and it gave me a P 0148 code. Must be the lift pump? Any advice would be greatly appreciated. If it is the lift pump what is the best replacement pump?

CRToney

Fass, airdog, BD, and GDP make replacement pumps. Some have additional filters which are good too. Check out the Glacier Diesel performance setup first. Find a post by AH64ID he has one of their systems on his truck with pictures if you click on that in his signature. He knows his stuff. Good luck.

Adam8361

Local diesel shop had OEM replacement lift pump on hand and for a good price so I ended up just putting another one on the back of the filter housing. Thought this fixed the problem but truck stalled out on the interstate and the fluttering idle never left. Unlike last time it completely quit running and wouldnt start. Got truck home and took out fuel filter and there was not fuel there. Sounded like lift pump was running empty when I cycled the key and I still had a quarter tank of fuel. I put more fuel in it and then it started. Is it possible to have a bad fuel sending unit?

Thanks