2009.Discovery 3 aux heater problem, it smoked one time when I first prompted it, but did not continue to full burn, I can test the function.with my computer, it says the module and heater are fine, but the pump test comes up as fail/re-try, I have had the pump off and it pulses when charged, I connected a tube to the fuel pipe and tried to suck fuel, but was unable to draw any at all from the tank, is there any reason other than a gunge blockage as to why fuel will not flow ? I imagine there is perhaps something to stop syphoning in the event of a leaking pipe, if not, will charging the line with an air gun help, or is there something in there that will be damaged by doing this.
any help would be gratefully accepted