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On my 2005 Duramax I used a 12 volt soleniod switch to control on/off flow. Had truck for 3 years, never did overflow main tank. Only problem I had is that the main tank would fill too much & trick fuel guage to thinking it was empty. Just have to shut off aux tank for a few km's to make fuel guage return to normal. Also make sure switch is only in on postion when truck is running, this will prevent overflow. |