Morris Minor Owners Club

Fitting a different tank and a sender unit in my van............will the single wire in the back that feeds the sender unit power a ford sender unit? Also will the gauge work? If not what is the best option? will the VR effect it

No replies, so here goes with some probably irrelevant thoughts.

There are basically two common types of electrical gauges - moving iron or rotating coil. The former require rather more current through the reading parts than the latter. Suitably damped rotating coil is the modern day norm for an analogue instrument.

The full scale deflection of any ammeter can be adjusted for full scale deflection (above its minimum current requirement) by using an appropriate shunt.

Your wire would, I expect, be OK.

Most sender units are simply a variable resistor. The guage will either indicate potential difference or current draw ( both rotating coil voltmeters and ammeters are basically the same device but with different shunt requirements).

Best option is to use the whole system and not worry about making electrical alterations.

Which VR? The voltage stabiliser of around 10 1/2 volts is there to avoid any changes in battery potential affecting voltage or current through the tank resistor, and will be adequate for any moving coil meter to stabilise the readings.

Many thanks oliver, its a Mk1 ford escort van sender in it

i have played with a 1980 ford fiesta 2 years ago and found the stabilizer to be equivalent to 5 volts to give a full tank reading, but the bmc stuff {morris] is equivalent to about 10 volts, dont forget the old type stabilizers actually pulse the power on and off, the on time is less when the supply volts is high eg reving engine.the very slow needle movement damps out the on off pulses

escort tank is much earlier than the 1980 looking at early 7o's would that make a difference

IIRC the voltage stabiliser on my J registered Mkl was 10 1/2 volts. It was one of the few parts of the car that were never changed...

many thanks oliver

Ford tank converted and fitted. Ford sender retained and its the fuel outlet as well. All works no leaks but 10 gallon capacity.

One small fly in the ointment.....fuel gauge showed 1/4 tank before draining. Now its shows 3/4 full? Same fuel. Is it reading in reverse?

Any ideas

They are a law unto themselves. New sender reads full for 200 miles then drops to 1/2 then to 1/4 and that is time to fill up as it could well be empty. Only shows empty when switched off!

Firedrake.....thanks for the reply however its an escort tank with a ford sender unit it seems to be working the opposite way around!

Note its not a 10 gallon built for a Minor using a Minor sender unit its been converted and all Ford parts kept, so I just think its working in reverse.

update

Tanks is reading in the right direction but false reading at gauge, simple reason is the resistance ohms on the sender units. see figures below

Ohms/Resistance on at (Empty/Full) 73-10 Ohms, applies on most pre-1989 Fords, whereas the Minor falls under Industry standard, works and operates at 240-34 Ohms.

That's why its reading high

When I have time ( unless someone beats me to it ) a resistor in parallel should do the job.....Product over sum if I remember correctly?

John

Sleeper wrote: ↑Fri Jul 06, 2018 10:39 am When I have time ( unless someone beats me to it ) a resistor in parallel should do the job.....Product over sum if I remember correctly?

John

You would have to add a resistor in series and that still would not work. Adding 160 Ohm in series would give the correct empty but when full may not even reach quarter.
Adding a resistor in parallel with the gauge would increase the current through the sender, may not be a good idea.

I think the best approach is to have a lower stabiliser voltage. As mentioned earlier some fords used 5Volts even in the early models.
If you’ve got a variable power supply you could do a mock up using it to replace the stabiliser.
If the voltage isn’t 5 volts any stabilised voltage can be achieved with a LM317 regulator.
It may still not give the desired result but I think it’s your best bet.
Regards John

Today I experimented with my fuel gauge and the resistances you quoted for the ford sender.
Unfortunately there isn’t enough range of resistance from full to empty.
What ever voltage I used as a reference I could only get half scale deflection.
5 Volts with 73 ohms dummy resistor gives a pointer position on the E marker and with 10 ohms the pointer manages to line up with the divide symbol the ½ written on the gauge.
With 9 Volt it gives full but empty still shows half on the gauge.
I think you’ll have to find I ford gauge and fit it as is, or find a way to fit it into your speedo.
Regards John

You would have to add a resistor in series and that still would not work. Adding 160 Ohm in series would give the correct empty but when full may not even reach quarter.
Adding a resistor in parallel with the gauge would increase the current through the sender, may not be a good idea.

Presumably that is why he said ‘in parallel’. Series only would not work, I would think.

I expect there is a suitable compromise that might include series and parallel resistors, but I haven’t the time to check out the possibilities.

Oliver please try! As I have said there is not enough range in resistance from full to empty.
I haven’t got a ford sender to experiment further, sure you could add a resistor in parallel (shunt) with the gauge and it would work but would send more current to the sender unit and most likely over load it. I wouldn’t want to recommend a fire risk.
I’m sure Sleeper was suggesting a resistor in parallel with the sender which would give the gauge more current increasing the reading further.
I also pointed out that a series resistor would not work, hence my suggestion of a lower stabilizer voltage that a have now experimented with to find that doesn’t work.

Sleeper.
I am not criticising you. You did say "unless someone beats me to it".

Russell
I’ve just had a look at the Morris 64 onwards sender on the ESM website.
I reckon you could find a way to graft that sender section onto your ford sender/fuel pickup unit.
Just trying to help.
Regards John

I have removed the Ford sender today and cut the attached sender off and I have grafted a Minor sender into the Ford housing retaining he outlet pipe......and it works.

The tank is 9.5 gallons and there is about 3-4 gallons in and it reads pretty accurate a lot of hassle but pleased it works.

Result

Sadly its decided to stop working...……...just a coincident?

Back in the '70's our 1200beetle didn't have a fuel gauge at all. There was a small reserve that kicked in at the flick of a switch,allegedly. Just carried a gallon of fuel in a can.