F550 Thor Class C RV. Replaced the fuel selector switch. I get correct fuel indications when selecting both tanks; however, the fuel draws only from the 2nd tank; which is also used by my generator. My manual says that it is an independent system. However, I cannot get it to draw from the 1st tank? Any ideas appreciated. Thanks.

 

I’m not up to date on the f550 platform but if it’s like the 250/350s there is a fuel switch on the dash and a fuel switching valve on the frame rail that will switch between tanks. The 90s era trucks used this and it was common for the valve to get stuck on one tank until the valve was replaced.

 

Thank you. I had the valve replaced. It could be a defective valve; maybe.