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MG MGA - Tank Sender Unit (Colyn)

A question mainly for Colyn but others welcome to comment. I need a new sender unit and I seem to remember you saying that you have a 'good one' with almost perfect resistances, can I ask where you got it? I am sure you have said this on BB but cannot find the entry with search.

Paul
Paul Dean

Paul,
Not from Colon but this may be what youre looking for. https://mg-cars.org.uk/cgi-bin/or17?runprog=mgbbs&mode=archiveth&archiveyear=6_2017.dat&access=7&subject=6&subjectar=6&source=T&thread=2017090421211925739

Jim
JL Cheatham

Ended up getting one from Holden, works for me
David k Brenchley

I think this is the thread from Colyn you are looking for
https://mg-cars.org.uk/cgi-bin/or17?runprog=mgbbs&access=&mode=archiveth&subject=6&subjectar=6&thread=2018071322574923959

Graham V

Sorry for the delayed response Paul, we were on holiday and away from wifi.

I got my "almost" accurate sender unit from NTG Services. IIRC it had a range of 0.5 to 72 ohms, which was much closer the correct 0 to 70 ohms than my old sender unit had.

This is the link to the thread I started about it at the time.
https://mg-cars.org.uk/cgi-bin/or17?runprog=mgbbs&access=&mode=archiveth&subject=6&subjectar=6&thread=2016080922300228304

(Jim and Graham, I couldn't seem to be able to open the links that you posted earlier, I hope that my link opens.)

Thanks for the name change Jim, I have never been named after a lower bowel before, I hope it was a typo, :^)

Paul, I still have the same NTG sender unit fitted but I have now also fitted a Gauge Wizard to the gauge which has made it completely accurate at the lower end of the range-where it really matters.

The reason for this is that although the new sender unit was much more accurate than my old one, it still didn't allow the gauge needle to drop to the empty position.
So, I was never certain of how much fuel I had left once the needle got to 1/8 full and I did run out of fuel a couple of times with that set up.

The Gauge Wizard unit has sorted this out and I now have a fuel gauge and low fuel light system that shows me when I have exactly 1/8th of a tank of fuel left. For me this is one and a quarter gallons or about 30 miles range.

Hope that helps

Cheers
Colyn


Colyn Firth

I just checked again and Grahams link is working ok, it shows the link to my Gauge Wizard thread which includes both the sender unit and the Gauge Wizard information.

The MGA fuel gauge is really sensitive to the voltage it receives from the sender and so your sender unit has to have a range of exactly 0 to 70 ohms for it to work accurately.

The beauty of the Gauge Wizard is that, even if your sender units range is a long way off the correct 0 to 70 ohms, so long as it shows a difference in resistance readings between empty and full, then you can programme the Gauge Wizard so that your gauge works absolutely accurately.

Cheers
Colyn
Colyn Firth

Colyn

You mean to say you have never been called an 'Old F**t' before?

Steve
Steve Gyles

More often than I would like Steve! :^), maybe its to do with me being in my 69th year. I must be looking like one nowadays!

Cheers
Colyn
Colyn Firth

Good news, I no longer need a new sender unit.

The problem was that after getting back from a 50 mile run on Sunday I had a bad petrol leak through the variable resistance cover. The bottom 2 screws wouldn’t tightened as if the thread was stripped. After sending this request I decided there was nothing to be lost by trying to force some slightly larger screws in as body is only softish alloy. . The result was the first slightly larger screw went in as if it was correct, and tightened. I then replaced 2 more of the screws, and the cover sealed ok. Before reporting back I thought I better give it a good shakedown which I did yesterday , i.e. another 50 mile fast drive, and all is still fine.

By the way while you guys down south have been having dreadful weather it’s been/is a gorgeous week up here.

Bizarrely I think the new screws out of my random screw jar are the correct ones for the thread which means the ones fitted by the manufacturer were wrong! Weird. The unit is only a few years old and reads acceptably. I think it came from Moss.

Many thanks to all and I think I may invest in a Gauge Wizard. I do by the way carry an emergency accurate gauge in the form of a length of half inch dowel that I calibrated some years ago.

Thanks again

Paul
Paul Dean

Paul

You mean one of these? Been in the family since the 30s I think.

Steve

Steve Gyles

Prehistoric!

Cheers, Barry
Barry Gannon

I bet it is much easier to programme than my Gauge Wizard Steve! :^)

Colyn

Colyn Firth

Just thought I would order a Gauge Wizard, not Steve style, but negative earth only. I know I could insulate it but ....

My dowel gauge isn’t polarity sensitive and always accurate!

Paul
Paul Dean

Paul,
the Gauge Wizard unit is in a completely insulated plastic box with no metal parts showing, so it would be safe enough to fit to your call.
However, before you buy one I would give Spiyder who make them a call, they are really helpful and will tell you if the wizard will work correctly on a -ve earth car.

If you do decide to buy one, let me know and I will send you my transcripted set-up instructions. The original ones are a little bit cryptic and so I decided to Transript their YouTube instructions which are much easier to follow.

Cheers
Colyn
Colyn Firth

This thread was discussed between 29/09/2019 and 04/10/2019

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