Talk Morgan Forums Thread Like Summary - Problem med gauge.

I have a Roadster 3.0 2010. I have a problem with the fuel gas gauge. When the tank is full it shows "Full tank" then the gauge doesn't go down until almost half the tank is used up. After that the gauge stops at half the tank, then the gas is gone. Has anyone else had this problem?

Greetings KimLake.

Yes, a common feature as Jon said. Whilst the cars do use well tried and tested Ford pump and sender units, from about 2005 it appears Morgan chose to stick a PIC microcontroller between the sender and gauge. My money is on the implementation of this ‘tech’ for the gauge feature.




The gauge on my old 2006 car wouldn’t come off of full until I had used about 3 gallons so decided to recalibrate the thing (a 2006 car is similar to a 2010 car in principle but has a different dash).

This is what I did. Filled the tank to the brim and then whipped the dash off. Connected a potentiometer in series with the gauge. Don’t think its too important which one of the two gauge wires you use, although somebody that knows about electrickery will probably correct me here... The POT value isn’t that important either although I think mine might have been a 5k that I had kicking around. Then with the ignition on, twiddled the POT around until the gauge needle just landed on the full point.




Whipped the POT off and measured its value then threw the POT back in the junk draw.




Replaced the POT with the nearest value resistor that I could find as a permanent fix. I used 15 Ohm here.




My gauge was quite normal after this little procedure.