Lost MPG, Need assistance/ opinions

[barbwire]

About 3 weeks or so ago, I started losing mpg, on my 04, to the tune of about 3 to 4 mpg . I have since changed the fuel filter, the air filter, and I make sure that I only fill with #2 diesel. I also have tried injector cleaner , and other additives. All to no avail, it seems .

Is it possible that my injectors are weak? Is it possible that mabe a failing lift pump can cause this? I do not have a fuel pressure gauge.

This would not be such an issue, but, fuel is a big expense for me. About $1000. 00 a month. So, I need assistance to trouble shoot the prob.

Any suggestion will be of great help.

BTW, it has 170,000 miles on it. Valves were adjusted at about 100,000 mi. Driving habits have not changed , nor have my routes.

TIA for any assistance/recommendations.

 

[RankRam]

I've read that a failing lp will cause a loss of fuel mileage, also I bet your area has switched to winter fuel in the last three weeks too.



BTW: I would check for a boost leak and low air press. in your tires.



Good luck, I hope this helps ya.

 

[Prairie Dog]

Winter fuel shure screws up my mileage, I loose about 2-3 mpg.



Scotty

 

[steved]

Winter fuel shure screws up my mileage, I loose about 2-3 mpg.



Scotty

It did mine too until I installed my FASS... for some reason the FASS made that "winterized fuel" mpg loss go away. And my fuel mileage doesn't fluctuate as much either...



Before the FASS, I'd go from the high teens to the mid teens in a single tank...



And we got to remember that new ULSD is supposed to be everywhere pretty soon... I'm sure that's not going to help any...



steved

 

[barbwire]

Hey fellas, thanks for the replys. But, winter fuel being a mixture of #1 and #2 is not part of the problem, because I have been diligent about filling with nothing but #2 only, as the places I fill at have the option of filling with either or.

Also according to my boost pressure guage, it seems to be putting out normal boost pressure.

Maybe the ULSD could have something to do with it, but I hope not. Because if it is, then we are stuck with lower economy forever. And I guess if it is the problem, then I would think that there would be a whole slough of complaints from thousands of diesel rig owners. So far I have not seen that.

As far as the lp is concerned, I thought I have noticed some "bucking" that I did not really notice before, so it might just be... ... ... .

On the topic of the lp, does anyone know where to find an OE lp for a reasonable price? I do not want to go with the in tank pump, as I can replace the original in a shorter period of time.

Thanks again

 

[BTighe]

have you checked other things like tire pressures in truck or something hanging up in the drive train. never mind, just read boost pressure is normal.

 

[JVas]

Check Driveline

Sounds like you have a U-joint binding up.

 

[Prairie Dog]

On the topic of the lp, does anyone know where to find an OE lp for a reasonable price? I do not want to go with the in tank pump, as I can replace the original in a shorter period of time.



You can get the orig pump at any Cummins dealer for about $120 if I remember rite. You can call them, do the whole deal over the phone and they'll just send it to you.

Only takes about 15 minutes on the side of the road to change it.

 

[barbwire]

Sounds like you have a U-joint binding up.

You know, JVas, you might just be on to something. I just had all three u-joints replaced about a month ago. And it sure made me nervous when they told me that they had to sand the cups down so the clips would fit the yokes.

They swore up & down that they were the right u-joints, though. I think ( if I remember right) that the # was 1879 .

But, how would a guy check them? Would they be hot after running a while?