TR2/3/3A TR3 fuel sending unit

[mallard]

TR3 fuel sending unit

I just got a new sending unit for the TR3 and I'm concerned about the design. It does not look anything like the original or the picture in the catalog from the seller. I don't like the idea that the electrical part could be in the gas for long periods of time. With todays gas that contains 15% alcohol. Has anybody used one and does it hold up? Also the float arm is about two inches shorter.

 

[mgedit]

Re: TR3 fuel sending unit

I do not have any direct experience, but I'm sure there have been earlier posts about people having issues with repro sending units. Just not sure of models that were involved. Cheers, Mike

 

[dklawson]

Re: TR3 fuel sending unit

The exposure of the electrical bits to gasoline (even with ethanol) should not concern you. There are several BMC cars where the sending unit is completely under gas until the fuel level drops below half a tank.

The length of the float arm may not be a problem either. If the limits of travel (X inches up, Y inches down) are the same, and the resistance range is the same, your new sender will work like the old one.

Out of curiosity, what is wrong with the old sending unit?

 

[TR4nut]

Re: TR3 fuel sending unit

I remember the same discussions as Mike, search for a thread on this - I do think you might want to send that one back Keith - it makes no sense to me that the unit would be that much shorter, even if it functions it would misrepresent the lower end of the tank volume.

Also, not sure if there is a topic on it, but be very leery of the plastic floats, with the E85 you mention - too many stories of leaks. There is a brass float out there that can be used which would be much better I think.

 

[NutmegCT]

Re: TR3 fuel sending unit

A couple thoughts:

Did the new unit come from one of the "big name" LBC parts suppliers (Moss, TRF, Victoria British)?

Seems that if the float arm is shorter than the original, the gauge would show "empty" before the tank is really empty. The short float arm would reach its lowest point *before* the long float arm would.

Tom

 

[mallard]

Re: TR3 fuel sending unit

Doug I tested the unit the same way I test the TR6 unit. I found an old BCF thread from 09 were you mentioned what to do and a link to the MGGURU. I think my testing method is wrong. I will look into it later.

Yes the new unit did come from one of the BIG3 and I do agree that the short arm will not measure correctly when the tank is low.

Randy the float for a 67 mustang is brass and will fit on the arm. I have the part number somewhere.

 

[martx-5]

Re: TR3 fuel sending unit

<span style="font-size: 17pt"><span style="font-weight: bold">Don't use that sending unit. Ship it back.</span></span>

I did (got it from Moss) and had to take it out and get a proper one. I explain it all in this link.

 

[TR3driver]

Re: TR3 fuel sending unit

From the photo above, it certainly looks like the float would not reach the bottom of the tank. I'd send it back now, since they may refuse to take it once you've installed (and found that it doesn't work any better than Art's).

 

[dklawson]

Re: TR3 fuel sending unit

Art, thanks for posting the link to the old thread. That is very informative. Perhaps this "new" sender is the same type as the one in your thread.

However, I still suggest measuring the total "up/down" inches of arm travel on both the new and old senders. Yes, the float arm on the new unit may be shorter but if it swings through a wider angle, it may still cover the same number of inches of travel as the original sending unit. It's at least worth checking with a scale and a multi-meter before shipping it back.

Keith, so what is the old sender doing wrong? Why are you replacing it?

 

[TR4nut]

Re: TR3 fuel sending unit

However, I still suggest measuring the total "up/down" inches of arm travel on both the new and old senders. Yes, the float arm on the new unit may be shorter but if it swings through a wider angle, it may still cover the same number of inches of travel as the original sending unit. It's at least worth checking with a scale and a multi-meter before shipping it back.

Doug-

If the arm is shorter, though, you'd reach the lowest point on the sender before you hit the bottom of the tank, so you might have 2" or so of gas still in there - I think it would give you a false empty indication, wouldn't it?

Randy

 

[mallard]

Re: TR3 fuel sending unit

Doug at this time I can't confirm that anything is wrong with the original unit. The unit was out of the car when purchased. I tested it just like I did the TR6 unit. I would test it with a meter and look for a resistence drop when moving the arm. I can't get any reading change with the TR3 unit. After some research it looks like the unit and dash meter have to be tested together. Since the car is apart can the tank unit be tested alone?

Art thank you for the link to your findings. I will return this one, and if needed try to find a good replacement.

 

[TR3driver]

Re: TR3 fuel sending unit

I can't get any reading change with the TR3 unit. After some research it looks like the unit and dash meter have to be tested together. Since the car is apart can the tank unit be tested alone?

Yes. You should be able to see the resistance change from nearly zero with the float all the way down, to around 100 ohms with it all the way at the top. If it doesn't change, double-check that you are on the right terminals and that someone hasn't left out the insulating washer. Otherwise, the sender is probably bad.

 

[mallard]

Re: TR3 fuel sending unit

Here's some more information on the fuel sending unit sold on ebay. I did as Art and others said to do. I sent the one with the short arm back, and ordered one from ebay. It seems to be the best on the market for now. As Art mentioned the holes are off, they are way off, and to small for the screws. With two phone calls and one e-mail thru ebay without a reply from the seller I was able to get this information. First of all if you drill out the holes so they will fit the screws you void the warranty. But in my opinion you need to drill 6 new holes in the correct position. They were also firm in the idea that there is nothing wrong with the sending unit. The problem is with the aftermarket tanks being sold have the holes in the wrong place. So if your not willing to work on the new unit I would not purchase one. And make sure you test it before you modify it at all.

Picture shows the original sending unit with the holes in the correct place, and the new replacement unit with the holes in the wrong place.

 

[martx-5]

Re: TR3 fuel sending unit

I guess that's where I differ, as I had no qualms about drilling the holes larger. It's not a big deal. As far as their orientation goes, yes they are off, but not enough to make it unusable. Just orient the arm facing more toward the rear. I didn't re-drill new holes.

Unfortunately, many of the replacement parts available for these fifty year old cars are not exactly correct and we have to learn to adapt or go without.

The unit from Moss fits well, but is useless for indicating correct fuel level. The one from e-bay needs a minor re-work to fit, but it does indicate fuel levels properly. Pick your poison.

As far as the warranty goes, I doubt that the dude from e-bay would be able to tell if the holes were drilled out, as IIRC, the amount needed to make the screws fit was not very much.

 

[NutmegCT]

Re: TR3 fuel sending unit

Does Moss know that their unit gives incorrect level readings?

Tom

 

[martx-5]

Re: TR3 fuel sending unit

Does Moss know that their unit gives incorrect level readings?

Tom

He does now. I sent Shawn at Moss an e-mail.

 

[ShawnC_at_Moss]

Re: TR3 fuel sending unit

Thanks for the heads up Art.

This hobby never ceases to amaze me. We have not had a complaint since 2007 on this product. We have certainly had some returns but not an alarming amount by any stretch.

On those of you who have used the part from NOS, doesn't it hit the side of the tank if you only oversize the holes? Or did you re-drill their orientation? They look like they are 30 degrees off.

 

[mallard]

Re: TR3 fuel sending unit

I'm going to make the ebay unit work because it seems to be a better unit, and others have been able to make it work. If you re-drilled to holes to the correct position I think you would have problems with the stud.

Shawn if you mount the unit as is you will hit the back of the tank. As mentioned above it looks like you can just enlarge the holes and point it to the back of the tank and it will work.

 

[martx-5]

Re: TR3 fuel sending unit

On those of you who have used the part from NOS, doesn't it hit the side of the tank if you only oversize the holes? Or did you re-drill their orientation? They look like they are 30 degrees off.

Yes, the holes are 30° off, but if you orient the arm toward the rear of the tank, there's enough room to where it doesn't hit the tank. At least that's my experience.

Edit: Shawn, maybe they haven't sent them back because, like me, they used them for awhile before they realized what was happening. Since I didn't drive my car much for the first after the resto, I had it in the car for over a year already...plus the time I had it before I installed it. I still have it in my spare parts collection. :laugh:

One more edit: I seem to recall having to have to flip the plastic float so it aims toward the center of the tank to give it more clearance.

 

[ShawnC_at_Moss]

Re: TR3 fuel sending unit

Got it. Writing up a product report this morning.

Shawn