Very Low Fuel Avg

[a2logistics]

HI.
I purchased Prostar 2009 Cummins ISX few months ago, it has 578,000 miles. and it was giving me very low fuel avg. it was around 3.75MPG. So i took to different shops to get it diagnosed. Everybody had different opinion about it. Since i purchased from a dealer, it had some warranty, And we found out that DPF filter was cracked so it was being replaced. and then engine was making some noise, when we open the head, it had some broken metal parts in it. Thank God it was covered under NTP warranty, so they replaced all the parts in it and the total invoice was for $19,000. Which NTP paid. and then i have changed fuel injectors on it and temperature censer etc.
After that it still gives me almost same Fuel avg. I have taken to few different mechanics, and no one could find anything wrong with it. NO air leak, no fuel leak, no oil leak. nothing
So Please give me Some suggestion, what should i do now. I am getting around 4 MPG. with no idling. i just can not afford to loose anymore money. and 3 different Drivers have driven the truck.

[Brock]

Before we talk about the mechanics. How much weight do you haul? what's your gear ratio? what tires do you run?

Obviously you have a major issue... major!

I was hauling 140,000lbs with 411 gears in a mile out engine that was doing a regen 8 timed a day and I was getting 3.5mpg so unless your hauling heavy, you got yourself a certified lemon.

[Waterloo]

Everything Brock said will play into your fuel economy... That said, I was getting roughly the same mileage on my 2008 Prostar, 4 to maybe 5 mpg with a tail wind. After ridding myself of the EPA mandate, I have gotten as high as 9 mpg pulling a flat bed. Right now, after the in-frame, I am averaging 6.5 mpg in a mix of city and very short haul driving, which I believe is pretty darn good for my set up. I normally do not haul more than a few thousand pounds, 53' dry van with a flat top sleeper, tractor has a steerable drop axle, along with wet kit and Tri Pac. She is set up to haul propane.

[Rawze]

(12-21-2016 )a2logistics Wrote:  HI.
I purchased Prostar 2009 Cummins ISX few months ago, it has 578,000 miles. and it was giving me very low fuel avg. it was around 3.75MPG. So i took to different shops to get it diagnosed. Everybody had different opinion about it. Since i purchased from a dealer, it had some warranty, And we found out that DPF filter was cracked so it was being replaced. and then engine was making some noise, when we open the head, it had some broken metal parts in it. Thank God it was covered under NTP warranty, so they replaced all the parts in it and the total invoice was for $19,000. Which NTP paid. and then i have changed fuel injectors on it and temperature censer etc.
After that it still gives me almost same Fuel avg. I have taken to few different mechanics, and no one could find anything wrong with it. NO air leak, no fuel leak, no oil leak. nothing
So Please give me Some suggestion, what should i do now. I am getting around 4 MPG. with no idling. i just can not afford to loose anymore money. and 3 different Drivers have driven the truck.

Problem #1 -- Your taking it to mechanics instead of solving your own problems as a truck owner.

Problem #2 -- You need to do ALL THIS STUFF!!! -- as a starting point to solving your problems...

http://rawze.com/forums/showthread.php?t...122#pid122


Most shops and/or mechanic could care less about doing that stuff. They are too hell bent on taking your money and replacing expensive parts instead.

[Rawze]

Has anyone bothered to check to see if your doser injector is not leaking fuel? - Very common issue with them as they get old.