Tito wrote:
Not much of an auto electrician. Was after some help please. When I turn my ignition on, I get a reading from my fuel gauge. (Built into the big central speedo) Once I start the car, the fuel gauge drops back down to zero?
I assume it may be a grounding issue somewhere. It may have something to do with the installation of the second fuel tank?
A nudge in the right direction would be much appreciated.

Check your earths, could possibly be the voltage stabiliser, which is mounted on the back of the speedo, ( its a small rectangle metal canister with 4 pins coming out of it )
I doubt that the second tank would have anything to do with it. I had a problem with the voltage stabiliser in my car ,where gauge was only reading half full, also the temp gauge
would only read about a quarter, changed it and now they both read normal, but in saying that ,every now and again both gauges decide to not work and they drop back to zero.