Fuel gauge is just an ammeter and they either generally work or don't so sounds like the sender or wiring at or to it is duff. Only way from the front is to remove the multiconnector from under the dash and measure the resistance from the pin that feeds the to the sender to chassis. Which pin depends on the year of your van and the reading you should expect depends on how much fuel is in the tank but a qaurter full tank should read around 150 ohms (or thereabouts). Chances are you will read nothing at all and then its time to get under and investigate further.
Last edited by AngeloEvs on 02 Oct 2009, 17:20, edited 2 times in total.
in nearside rear wheel arch is connector to tank sender on side of tank, easy enough to remove but be aware they can be mega corroded and snap off, you should then be able to check reading on sender and check continuity front to back, but sounds like possibly float has a hole in it and doesn't float fully or the potentiometer in the sender has died