MF135 diesel
New User
This is in response to an earlier question about a MF135 fuel gauge. The original setup used the 4th terminal of the voltage regulator with a
resistance to lower the voltage to the gauge. I learned this the hard way when my original voltage regulator failed and the new one was all solid
state and the resistance circuit in the 4th terminal was absent. So I used a potentiometer which is a variable resistor that can be adjusted to
give the amount of resistance needed to get the correct voltage for the gauge to read properly. Pictured is the type of Pot that I used and as you
can see the shaft is what is turned to adjust the resistance. You can google potentiometer and there will be many choices available for ordering.
You dont need an expensive low variance one
I placed mine inside a little metal box behind the battery holder next to the dash. I did this because I have a problem with mud daubers building
nests all over my tractor. As illustrated you solder the power source wire to either the left or right side terminals and the middle terminal is
wired to the fuel gauge.
Since you do not want the fuel gauge on when the tractor is not running, I got my source of power from the outmost terminal on the starter
solenoid. This has no power when the engine is not running because it is spliced into the wire from the oil pressure switch which is an open
circuit when there is no oil pressure.
I would also check your fuel gauge sending unit in the tank to see if it is working. You will need an ohm meter to see if the ohms change as you
raise and lower the float. I had to replace mine as it was corroded and not reading properly.
t
resistance to lower the voltage to the gauge. I learned this the hard way when my original voltage regulator failed and the new one was all solid
state and the resistance circuit in the 4th terminal was absent. So I used a potentiometer which is a variable resistor that can be adjusted to
give the amount of resistance needed to get the correct voltage for the gauge to read properly. Pictured is the type of Pot that I used and as you
can see the shaft is what is turned to adjust the resistance. You can google potentiometer and there will be many choices available for ordering.
You dont need an expensive low variance one
I placed mine inside a little metal box behind the battery holder next to the dash. I did this because I have a problem with mud daubers building
nests all over my tractor. As illustrated you solder the power source wire to either the left or right side terminals and the middle terminal is
wired to the fuel gauge.
Since you do not want the fuel gauge on when the tractor is not running, I got my source of power from the outmost terminal on the starter
solenoid. This has no power when the engine is not running because it is spliced into the wire from the oil pressure switch which is an open
circuit when there is no oil pressure.
I would also check your fuel gauge sending unit in the tank to see if it is working. You will need an ohm meter to see if the ohms change as you
raise and lower the float. I had to replace mine as it was corroded and not reading properly.
t