View Full Version : Fuel gauge not working

04-02-2014, 08:39 PM
I replaced the fuel gauge sending unit on my 2004 x9 and it still doesn't work. It is a 3 wire unit. The gauge just stays on empty and I have a 1/2 tank of fuel. Read some of the threads on here and can't even figure out what an mdc is. Any suggestions how to test the gauges or circuits?

04-03-2014, 07:29 PM
problem seems solved the fuel gauge decided to work. I am thinking maybe it needed to be cycled a few times

04-03-2014, 10:13 PM

05-22-2016, 01:49 PM
My x9 fuel gauge stopped working replace the sending unit 2 years ago now same problem gauge reads empty with 1/2 tank of fuel.I Just Replaced gauge and still does not work. I am only reading 6.78 volts on the hot wire going in to the gauge itself. Not sure if these should be ac volts or dc? Any help? Above post from a couple of years ago

05-23-2016, 09:50 PM
Anything in a boat/Car with a battery, will be DC volts…Using a multimeter, set it to read DC volts. I just wish MasterCraft would retrofit some of the gauges for us…Cant be that hard…and would make a lot of MasterCraft owners happy…sometimes one step back to go two steps forward…or come up with a way to better explain what is wrong…and how to fix.

05-23-2016, 11:22 PM
Here is a great little piece of info from the sender manufacturer.


The amount of ethanol in the fuel affects gauge accuracy! The voltage for the Multimeter would be set a VDC. I THINK 12vdc = full, and 0vdc should be empty. I took my sender out of the tank and calibrated it in a jar of fresh gas. Dipped it all the way in and set the full, took it out and set the Empty. Then put it in the tank and fine tuned it. In my V-drive I can see the fuel level through the plastic tank and actually set it to read "E" when there was visibly about 1/6th of a tank left (5 gallons). There is another PDF around here somewhere that shows the sender calibration procedure. I'll bump it if I can find it.

05-24-2016, 12:26 PM
Thanks wasn't sure on the voltage as the computers put out ac voltage (I think) and didn't know how they tied the gauges in to the computer system

05-24-2016, 03:06 PM
I am still reading only 6.5 volts on the hot wire both at the sending unit and at the gauge plug.
It would seem like this should read 11.6 v Not sure if this reading is correct all the other gauges work fine and all fuses are reading 11.6 volts with engine off key on. I don't think the 3 wire sending units have an adjustment please correct me if i am wrong. I don't know what to check at this point. My wire harness has pink purple and black going from back of boat to gauge, but the sending unit has red white black... red is hot white is sending and black is ground Any help here?

05-26-2016, 06:47 AM
The boat has an alternator, which produces AC ~ but is converted to DC right then and there and goes to the battery…anything connected to a battery, supplied by a battery is DC volts…computers included…hopefully other will chime N to help you on your gauge…keep searching and asking, you will get it figured out.

06-08-2016, 04:21 PM
If you look at the bulletin referenced above there were 2 senders that were produced both 3 wire. The "newer" style reads about 7 volts full and the other reads 12 volts full.