false reading

Hi all I have just bought a SL55 2004. Fuel always reading 3/4. My friend has a Chinese knock off Star System. I followed the star step by step to diagnose. I diconnected the plug on the fuel sender unit on the petrol tank and put various resistors on the plug socket from 51ohms to 1000...

Hi Guys I have just bought an 2004, SL55 AMG. The fuel garage keeps reading 3/4 but goes zero when ignition switched off. So I suspected the sending unit. One from eBay on the way. Starting stripping the rear boot carpets in preparation. Looking at it I pulled the connector off the sender...