Poor fuel mileage?
 

My cummins diesel just simply loves diesel fuel. I'm totally stock except for an up graded fuel pump, fuel and oil pressure guages and a new vp44. Starts on first hit and idles smoothly. When it was new it was getting 20 mpg unloaded. Now I get around 12 mpg which is not good.

What should be done to increase fuel mileage? If you know, please tell me.

Thanks, Kerley

I would seriously look into purchasing an Edge EZ, this chip will advance your injection timing and increase your mileage. I also run Lucas Fuel injection stuff in every tank. this should help your mileage.

I think apart of your mileage loss can be attributed to winter fuel. Do you guys get winter fuel down there?

Even so, something is not right.

I agree, 12mpg is pretty bad, something is going on.

Did it do this all at once or did it do it over time? Down on power maybe? Vp44 just wore out and not giving it the timing it wants?

How much was the VP-44 upgraded to? who did the work? If at all possible did this happen after the upgrade?

The shop that replaced the vp44 really ripped me off. I broke down on the road and had no real choice. The vp44 was replaced about two thousand miles ago. Ran just fine. After being raped by the diesel repair shop I started reading all I could find on Dodge/Cummins engines, and joined Diesel Bombers. Sence the vp44 replacement I have installed Autometer guages and the Fass DDRP fuel pump and I am happy with what I have. Fuel pressure at Idle is 25 pounds and at wot 19 to 21 pounds. She idles just as smooth as can be and runs out very well but the fuel mileage just sucks. I don't know what to do. I don't know a good diesel mechanic and don't trust the ones that installed my vp44. I need some help. Kerley

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I really don't know about the winter fuel but I do know something just Is'nt right.

Imagine that - a "shop" ripping people off.

do you have any boost leaks?

You have a good sence of humor, Yes the dirty [45ro0vtnivtovt5,p] ripped me off. They also stole the step off my drivers side and spilled something on the hood that ate the clearcoat off my paint. I raised all kinds of hell and they said, [ prove it.] They did eventually replace the step after I suggested contacting my attorney. Kerley

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I really don't know about Boost leaks. Kerley

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I don't know.
Not to change the subject from the Dodge/Cummins, but I have been running on road diesel in my tractor sence new and allways had a little rattle in the engine. This week I bought some "off road diesel" and the rattle is gone and she is purring like like a kitty with no added additives. Kerley

I am getting about the same mileage in my truck. I am pretty sure its my trans that is slipping. I just put on a new Vp44, raptor, hughes 15lxfm torque converter, edge comp, gauges (except trans gauge) intake, exhaust, rv275 nozzles, and 33" tires. my mileage started off around 18-19 but slowly got owrse after the 33" tires. Initially it dropped about .5-1 mpg from the tires. and slowly lost mpgs every tank, then i put my rv275s in and gained another mpg or 2 so it was back up to 15 but has since drorpped back to 13. I am sure it is my tranny starting to slip worse and worse. My RPM are about 2-300 (1900-2000) higher than they should be at 60 mph. when installing my tc the fluid came out Black, after installing my tc I adjusted my bands and the front band was adjusted at almost 4.5 turns from 6 ftlbs of torque! should only be 1.5 or so it made a huge difference in driveability but not much in mileage but I am almost certain it is because my trans clutches are too far gone.

since you have a manual I would take a look at your clutch. if its a newer clutch double check the engagement point. Also check your valve lash and adjust accordingly. it is fairly simple to do this stuff yourself you just need the confidence and a haynes Manual never hurt anyone. Plus it will save you some serious bucks!