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Old 08-21-2018, 12:50 PM   #9
GreG L.
Montana Fan
 
Join Date: Jun 2018
Location: Jacksonville
Posts: 382
M.O.C. #21993
Quote:
Originally Posted by pjames32 View Post
I have a 42 gallon in bed tank with a small tool box on top that I bought from Northern. It is hooked up to gravity feed with a manual valve that I usually leave open and just fill as needed thru the aux tank unless the main tank is down. ONE PROBLEM I have is the truck's computer will often show a check engine signal when running on the aux tank. It senses the truck is running but not using fuel! GM and my dealer cannot find the issue so I live with it. This did not occur with my 2007 Duramax and does not occur with my friends 2012 Duramax. Mine is a 2014 Duramax so YMMV! This does not affect the fuel mileage calculation, but does drop the fuel gauge to empty until you start using the main tank. The check light resets on the first restart after you start using the main tank.

This is a known issue with gravity feed systems, also overfill and line leakage that you cant tell until you stop. Not recommending Transfer Flow but they have a good write up on gravity feed tanks in the center section of this page https://www.transferflow.com/regulations

Yes you have to look past their sales pitch but still good information.
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