Engine cutting out when reverse gear selected

Hi All, I wonder if anyone can shed any light on this little problem I'm having:
It's only just started happening to my 1993 Ford Escort, manual 5 speed.
Whenever reverse gear is selected, the fuel gauge on the dash drops to empty and the engine cuts out!!
When I deselect reverse the fuel gauge goes back up and the engine can restart!
What the hell?!?
Any ideas please??
Paul.

this is gunna sound weird and i might be way off, but get under the car and have someone shift the tranny into first and back a few times with the car off. find the linkage (the moving thing) and then have them shift into reverse. it might be crimping a line thats out of place. that still doesnt explain the fuel gauge reading, but give it a shot