[naturalextraction]

Actually you may be heating the fuel so much you're getting perculation in the line which is real common in relation to the expansion rate of C8H18 and its other chemical additions. This will overcome the fuel pumps rated pressure.
BTW, most attempts at heating fuel via these methods, often negate negative results. Helping to disassociate fuel molecules becomes much more complicated than just adding heat or trying to get the fuel to absorb heat energy. Petrol, having internal chemical energy, has more properties to control at different levels of heat absorption, making it much more difficult to control. Something to think about.