165 Fuel Gauge not working - sender or gauge bad?

[whitedirt]

How do I tell which is bad, the gauge or the sending unit? I took the sending unit out, and the float is good. I used my digital multimeter, and while moving the arm up and down, the resistance seemed to change the entire time I was moving it. I can't remember the entire range it went, I know it was open at the empty side, but I don't remember the resistance at the full position.

I cleaned the ground strap at the top, so it should be properly grounded. It makes me think that the problem is the gauge, but before I buy the gauge, can you tell me if there is anything else I need to test?

 

[Gearhead210]

I believe that if you ground the wire on the sending unit, the fuel gauge should shoot all the way to the full side, if it does then the gauge should be good. Maybe someone else on here can verify that?

 

[Nick Martin]

Make sure you have power to it. That was the last thing I
checked and it would have saved me a lot if time. The oil
pressure switch on the back of the oil pressure gague was
bad on my 175.

 

[DavidP, South Wales]

Hi,
Gearhead 210 is correct. If the wire on the sender is put to earth the gauge should show 'full' if working. Check the electrical supply to the gauge and all connections. Make temporary wiring connections with the sender so that it can be operated outside of the tank to test it. Check for excess wear in the float arm pivot. This can make or break the connection.
DavidP, South Wales

 

[MikeNL]

My 165 sender unit did'nt work because the wiper was broken. I ordered a 897398M91N which was not an origional MF part, but looked like the one in my parts book. This did'twork correctly but I decided to live with it until I had the hood off. Finally got round to it, all connections and wires were ok but the sender was completely rusted and the float was full of diesel - not happy! I think the damaged sender has burnt out one of the coils in the meter. Even less happy!
I've scanned the old posts and only found one from Evan – “1972 135 sender = 0.5ohm to infinity” and a warning not to short i/p directly to earth to avoid damage. And this one from Eric – “I don't think all 100 series are the same. I bought a replacement for my 1964 135 and it measured 0-30 Ohms. It looked different than the original and after doing some digging I think the replacement is for a 135 UK. In my case the fuel gauge was the cultprit so I stuck with the original sending unit which turned out to be 30-240 ohms.”
My newest one measures 0 to 30 ohm. This however cannot be correct for a tractor made on mainland Europe as my other tractors read about 80 ohm half full (measured with a fluke meter) and the meter coils on my 135 measure 240 ohm.
My conclusion – There are at least two types. You can easily measure the sender, but the FSD current is not usually marked on the meter. Measure the resistance of your meter coils and if in doubt connect a resistor of at least 30 ohms in serie when you try it out.
My two euro's worth - Mike.

 

[whitedirt]

Ok, I finally got back to where the tractor is, and I've got more questions now.

I shorted out the wire, and nothing. So I got to thinking it was the gauge. After that, I started checking some voltages. The wire that goes from the regulator to the gauge is barely getting any voltage (0-1.5V). It can't be hooked up wrong because there is only one way for the 4-wire plug to hook up to the regulator. The terminals on the regulator look to be F-2-3-4, with #4 being the one going directly to the gauge (nothing else on that wire). Regulator is only a few months old, but I'm sure that doesn't mean anything.

And for what is worth, hooking the gauge to 12v power results in the gauge jumping to what should be in the tank. Should it be 12v to the gauge, or is it needing something else?

 

[Inno]

Yes, I believe it should be 12V to the gauge.

 

[ice cream man]

Hey ya"ll, I"m new at this so bear with an new tractor owner. My 165 has 2 of the wires going to the regulator cut and repositioned to others. Im not sure if the 1970 had a generator or alternator but mine has an alternator now. The only gauge that doesn"t work is the fuel gauge and it"s the only one still hooked to the regulator. With the tractor running I took the wire off the tank and touched it to metal but got nothing. I have no idea what else to do. Could the problem be the regulator and if it"s bad what"s that cost??