Forum Discussion

Explorer

Feb 15, 2014

Auxillary Fuel Tank

Hi all, new to this forum and welcome some comments, advice etc. Here goes. I have a 2010 GMC Sierra 4WD 6.0 liter with the manual/standard transmission. Tow vehicle we wanted for some time. bought it used and does everything I need. Anyway, sorry, back to eh help thing. I added an auxillary tank / box so we have extra gas with us where ever we go and to lengthen our possibilities of off the beaten path trips. my problem is that the "CHECK ENGINE" light comes on periodically when the gas in the extra tank gets down to less than half about 8 to 10 gallons. My theory, the extra air space in the aux tank is too large to allow the truck equipment to sufficiently maintain vacuum, so question at hand. Is there a way to add a vacuum pump, or something to strengthen what is already in the truck? We have had a smoke test done and already replaced a line that had a itty bitty leak, and double sealed around the fill neck. Gas cap is new and all works great. Anyone else with this issue? advice, etc????? Thanks from here and as always Good Luck & Be Safe ! ! !

15 Replies

jffkrn
Explorer
Feb 17, 2014
All the caps are on and the aux cap is non vented but all tied into the main tank and plumbing assembly. Should be and is tight. not sure of how many cycles it makes before resetting the light. Good Luck & Be Safe ! ! !
bound4fl
Explorer
Feb 17, 2014
Not sure of all the right teams, but when you leave you fuel cap off it will set off the ck light too. I think it has to do with all the emmision stuff on the newer trucks
jffkrn
Explorer
Feb 15, 2014
thanks for the replies. The aux tank sits in the bed, top inside of tank has a typical assembly on it with barbed hose fittings with tubes to the tank. The tubes connect to hoses, one to the pump and one to the vacuum side. hoses are fed through the bed into the original fill neck by an adapter with hose connections. So when the switch is flipped the fuel is pumped out of the aux tank into the neck of the fill for the truck. you can fill while driving or whatever. Thanks again and Good Luck & Be Safe ! ! !
mwool
Explorer
Feb 15, 2014
My aux tank auto fills main tank and I do not see this action. I have had bad fuel and chk eng light would come on at times. More when tank got lower vs full.
Bob_Vaughn
Explorer
Feb 15, 2014
How is the tank connected to the main fuel supply, In my research I was told I could not connect an auxiliary tank to the main fuel supply lines....