91 Convertible cuts out on left hand turns? Cuts out like the key is turned off not like it has run out of gas ( no spluttering) Only cuts out when I'm pulling some Gs (not when maneuvering) so I don't think it a wiring issue in the steering column. Has any one any ideas on where to look first?

 

From the FAQ:

 

Do a search for fuel sock or fuel filter. Generally, one cause of this problem has been reported to be partially clogged fuel socks. The fuel sock is attached to the bottom of the fuel pump located in the gas tank. You will need to remove the fuel pump and replace the sock. You can get get a replacement sock from a dealer or MazdaTrix.com.

Get a copy of the factory service manual if you don't have one.
http://wright-here.net/cars/rx7/manuals.html

 

Check the main fuse under the hood to be sure it isn't that. I had a similar problem; my car would cut out during drifting and hard G's. Turned out the main fuse was loose.