My problem is I only have as much rise as yours would if the fill cap was where I drew the red X below.I just did my 3500-HD like this and no problem filling at full throttle. The main tank is top inlet with a molded 90* hose .
So i have a 2" 45* then direct to a 2" 90* to around 2ft of straight pipe and then the molded rubber 90* to the tank . The 5/8" vent hose is about the same length that goes on the filler kneck .
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