TR2/3/3A fuel sending unit

[carpecursusII]

Can I use a tr4/4a sending unit in a tr3 without any changes or do i need the TR3 unit. Moss shows different part numbers as well as TRF. I have the one with a full length arm on the float like this.

Do i need this?

 

[Marvin Gruber]

You have to use the TR3 sending unit with the TR3 gauge. Different resistance in the TR4 sender. I just used an early TR4 gauge with TR4 sender in my TR3. A working TR3 fuel gauge is getting hard to find.

Marv

 

[TR3driver]

Right. Not only different resistance, but the resistance moves the opposite way. On a TR3, low resistance is empty, while on TR4-6, low resistance is full.

As noted, the early TR4 gauges look almost identical to the TR3 ones. But you will need a voltage stabilizer as well, for proper operation.

 

[martx-5]

The fuel sender in the bottom photo looks like a Moss unit that I bought a few years back. If you have that unit, do not use it as it will not function properly. I don't know if Moss has straightened out the situation yet. I did explain to Shawn over there what the problem was, along with pictures. I wound up buying one from a guy on e-bay that worked fine.

Here is the thread where I explain what the problem with that sender is....

https://www.britishcarforum.com/bcf...3-Fuel-Sender-From-Moss&highlight=fuel+sender

 

[TuffTR250]

I got the same kind of fuel sending unit from TRF and it also had the float arm that was too short. So I made my own wire arm that put the float at the same length as my original TR3 sender (which was totally rusted and would not move). The wire just snaps into the top plastic control mechanism. I had some rubber coated steel wire that was the same gauge as that in the TRF sender. I do not remember at all where I got it. I stripped the rubber and bent it to the shape of the TRF unit as well as my original so the float would end up in the same location. I took the plastic float off the TRF unit and bent the end of the wire too fit around the plastic float. I hope I don't regret not using a new brass float. But so far so good. The gauge is not 100% accurate but quite close. I prefer it the way it is since when it shows empty I still have about 2 gallons in the tank, (a rough estimate).
Regards,
Bob

 

[croz]

I also installed the TRF unit. The fuel gauge reads empty when there is still a lot of fuel left in the tank. 20 L is one heck of a reserve!
Moseso, thanks for the tip about the online seller NOS Locators. I've ordered one of his TR3 units and will fit it closer to spring.
Cheers, Steve

 

[PatGalvin]

Hi Guys
On the same subject....

I bought this one on EBay a while back. 1) Does anyone recognize this fuel sender? Was supposed to be for a TR3. I can put power to it and the fuel gage and test it, at some point. And 2) I seem to have two gaskets in my "parts bag". One is thin rubber and the other is some sort of white polyethylene or vinyl or ?? Thicker and more rigid. Anyone have experience with the white gasket or am I good to go with the rubber one? (I just can't remember which came with my EBay purchase).

Sorry, I know these questions are a bit lame.

Pat

 

[carpecursusII]

Pat, I installed my gauge which came from VB but i think they are all the same. It seems that the arm does not line up with the tank at a 90 degree angle, it points toward the back center of the tank. Is that right???

 

[Marvin Gruber]

Doesn't matter as long as the arm has full travel

Marv

 

[AEW]

I think "full travel" is the tricky part as far as accuracy goes. When you're fixing old ones any way. I built the test emulator gadget described on the MG Guru's page (most of the logic is the same for Triumph). But having to guess what equals full travel makes it less accurate. I will have get around to dragging an empty tank into the garage and poking a hole in it to measure the actual travel potential I suppose. Getting gauges just to read was enough of a victory at the time.