...I have filled up probably about 10 times so far and each time the overhead computer is (in my favor) estimating incorrectly the average miles per gallon.<br><br>The last two tanks of fuel I have purchased area as follows.<br><br>330 miles 18.5 gallons = 17.84 mpg and the komputer says 19.4.<br><br>221 miles 13.8 gallons = 16.01 mpg and the komputer says 18.4<br><br>PErsonally I like the numbers the computer gives in favor of the ones I am actually getting.<br><br>Anyone else having the big descreptancies? Is it normal to have these fluctuations between pencil and paper calculated and the overhead computer?

 

I have had the same difference. Filling up and doing the math can also be off. With all the foam it is hard to know when it is full unless you see the fuel in the neck. I don't have that much time so I figure it is between the two numbers.

 

That is something I noticed.<br><br>When filling the pump shuts off way before the rig is &quot;full&quot;.<br><br>I then add another 1/2 to 3/4 of a gallon to top it off when I can see the fuel in the neck.<br><br>That way I know I am getting closer to the same amount of fuel in the tank each time I fill giving me a little better guesstimate on the mpg numbers.<br><br>I started this trick with my prior Chebby diesel.

 

Are you resetting the computer with each fillup? I have let mine average out for the past 1000 or so miles. I am only off about .3 mpg.

 

Yep, the avg mph, DTE, ET and so on. <br><br>Basically whatever is capable of being reset.

 

Is it proper to fill the neck of the tank? I believe it states in the owners manual to stop at the automatic shutoff. What is everyone doing concerning this and just what is the problem, if any, of filling the tank neck? On my previous Cummins I have always filled the neck as long as I was not going to let it sit immediately after filling.

 

<br>Hummin Cummins wrote:<br><br>When filling the pump shuts off way before the rig is &quot;full&quot;.<br><br>I then add another 1/2 to 3/4 of a gallon to top it off when I can see the fuel in the neck.<br><br><br>You musta got the wrong tank in that truck. half a gallon is way before full??? <br>Computers are only a gaget that they can charge u for. As far as they are concerned &quot;close counts&quot;. Mine stays on temp and direction. And even those I take with a grain of salt...<br><br>

 

[quote author=Hummin' Cummins link=board=17;threadid=11467;start=0#108930 date=1046195749]<br>...I have filled up probably about 10 times so far and each time the overhead computer is (in my favor) estimating incorrectly the average miles per gallon.<br><br>The last two tanks of fuel I have purchased area as follows.<br><br>330 miles 18.5 gallons = 17.84 mpg and the komputer says 19.4.<br><br>221 miles 13.8 gallons = 16.01 mpg and the komputer says 18.4<br><br>PErsonally I like the numbers the computer gives in favor of the ones I am actually getting.<br><br>Anyone else having the big descreptancies? Is it normal to have these fluctuations between pencil and paper calculated and the overhead computer?<br>[/quote]<br><br>Yeah, me too! I think the computer was designed by a liberal Democrat. heh.