The fuel gauge on my '93 240 seems to have a life of its own, it sometimes reads fine , but the majority of the time it just reads empty, occassionally showing the right reading then dropping again. I'm sure I read some where this was caused by a blocked vent pipe? Anybody have any knowledge of this, or any ideas to sort this problem?

Suspect bad wiring or perhaps broken sender/guage-put low powered test light ontosender terminal at tank, and you should see regular pluses comming through. connect testlight earth to chassis, disconnect sender wire from terminal and briefly apply testlight to the wire-should be a steady glow, and perhaps a reading on the guage- if erratic, fault between sender and power via guage. run motor briefly to prvide some vibration-that may show a bad wire up. If OK, then reconnect sender wire to terminal on tank, and reconnect the testligh t to the them and ground. You should see regular pulses in the glow. If they are erratic, then the sender is prob shot, if not there, likewise. Usually causes are bad wires/fuses, senders and guages do fail, but they're rarer. Inspect guage for damage, and instrument cluster board for cracks (in the copper) by holding it up against a bright light (NOT the SUN!!) and looking closely. Do NOT Bend it!!!!!! Check all connectors on and to the board, pull lightly on wires to make sure they're properly crimped into the conector and making contact. I would suspect the pin connections to the board where the connectors plug on, as they get stressed during cluster install/removal. If you see a crack/corroded connection, take it to a TV repairman, and ask him to clean and resolder it. It will prob cost you 15 min max for a small job, but he'll be able to do it. Auto electirians will prob try to sell you another board, which you may not need. Any major break in the board is grounds for concern, but you'd have more wrong if that were so. WARNING: the big connectors are usually held captive to the board to prevent them falling off accidentally-you'll need to work out how to unplug them, as you can't see, and if you just pull, something expensive will break.