Hi All I am rewiring a twin engine boat. It is a 30 ft speed boat with twin Mercedes diesels. I have replaced all of the gauges and fitted a gps speedo. I am struggling to find the correct way to wire the fuel gauge and the speedo. I have separate ignition switches for each engine. The gauges (rev counter, oil, water and temperature) are also separate for each engine. Can anyone tell me the correct way to connect the speedo and the fuel gauge?

all the grounds should be connected from side to side. the positive power for the speedo and fuel gauge can come from either engine, just pick one.

HI is there a way i can connect it to both ,so that they cum on with ether engines is there an industry standard way to do this ? without getting feed back through the gauges

yes their is,,you can either use releys or the easiest way is to use a diode on each power wire coming from each ignition switch..the silver stripe goes towards the gauge..these wont allow power go backwards only forwards..check with your local radio shack... http://www.radioshack.com/product/in...erValue=Diodes

HI thanks for that . just in case the diode blows or goes wrong should i put a inline low amp fuse on the pos wires?.

yes,,any power wire should be fused..