Yamaha Fuel management / Raymarine C-70

I am trying to hook up my Yamaha fuel mgmt guage to my GPS (Raymarine c-70) so I can do real-time MPG info. Problem is, I can't find the wiring info. Raymarine advises that the MNEA OUT+ is (yellow) and the NMEA OUT - is (brown) which should typically be connected to the NMEA IN+ and the NMEA IN - leads , but Yamaha says to connect to the white lead on the Fuel Mgt Guage. So which MNEA OUT from the Raymarine c-70 should be connected to the Yamaha white wire? Yellow or brown? Can anyone help? Thanks

[boats.net]

Most of new electronics have multiple NMEA leads for connection to different units. You probably need to contact Raymarine for advise.

I checked with Raymarine, the engineer there said to contact Yamaha, but I cannot find a site where I can ask them What I need to know is: Should I Uses the plus NMEA out or the minus NMEA out? I am sure that I can't be the first one to try to connect a C-70 to the FMS guage.
Thanks for the reply