As far as I can tell, change from woven finish, and also the speckled woven wrapping for loom, to PVC finish and PVC tape wrapping occured in early 1964.

Mine is first half 1964 (car number 45xxx). I’ve seen the woven covering on many wires on the loom. It does make it a bit tricky now as the covering falls to pieces and the wire underneath is a different colour

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Sounds about right. Drawings are always in advance of production by a few months. In mid 1964, changes to local content rules resulted in many changes to the Morris 850 (baulk ring synchro, clutch, local steering rack, etc). The earlier cars had UK wiring harness (5L part number) whereas the tape wrapped looms were AYA part numbers signifying local production.

Last little item to add before I repair the loom:

I peeled back all the wires to their individual runs and taped them to cover any exposed strands. I checked that the fuel gauge was reading correctly and this was the result:
Both wires on sender: fuel level half
Green/Black wire only: fuel level half
Ground wire to green/black: fuel level zero

I don’t know if that means that I have earthed the fuel tank elsewhere or if this points to a faulty sender. Or perhaps the wiring isn’t right at the gauge end? More investigation needed!

Just to add, I did replace the cork sender gasket a few years ago so don’t know if that caused the sender to be earthed

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I think it suggests that your ‘ground’ wire isn’t grounded ? Have you done a continuity test on it ?

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1966 Mini Deluxe - “Gabby” 34 years under restoration and counting...
1970 MGBGT
1959 MGA

Thanks, that’s a good idea. I haven’t checked continuity from the ground wire to the body. Edit: results below

I did check that there was 12V from the fuel pump earth wire to the fuel pump white wire. (Although this doesn’t prove the ground is ok if the wire is earthing at the sender)

I also remember reading somewhere that the early pre-stabilised gauges worked backwards compared to the later senders, so grounding the sender wire would make it read empty rather than full (Edit: I’ve confirmed this with more reading now)

I checked the wires at the fuel gauge end and they are all fine - GB on the T terminal and 3 x green on the B terminal

Continuity checks:
Fuel pump ground wire to sender earth wire: yes
Fuel pump ground wire to sender stud: yes
Fuel pump ground to body: yes
Tank body to body shell: yes
The only slightly strange part here was the tank and sender body were all earthed. This would mean the possibility that the earth wire from the pump to the sender carried all the current from the pump at some stage and caused the wire to melt. The mystery remains as to why the power wire didn’t melt too

Fuel gauge checks were all normal for an unstabilised sender:
Green/black removed = full tank
Green/black grounded = empty tank

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Timmy.
I can't help with the fuel pump wiring, but I made some resistance and voltage checks on the fuel gauge wiring on my 65 S a few years ago. It has a fixed 10 volt "Voltage Stabiliser". The Mini Standard Saloon has an "Instrument Regulator" and the 850 DeLuxe Saloon has a "Bimetal Instrument Voltage Stabiliser" according to my Leyland Aust wiring diagrams. These switch on and off to give an average of about 10 volts
The fuel gauge resistance is about 60 ohms and the sender unit is about 35ohms full and 250 ohms empty.
It might be easier to just measure the voltage at the (Green/Black) lug on the sender; about 4volts full and about 8-10 volts near empty. These will vary down to zero every few seconds as the stabiliser switches on and off.
Can someone reassure me that the "woven cloth" covering the wiring was NOT asbestos?
Good Luck Dave D

I am 99% sure it is not asbestos. Unless there are tiny particles in it but the main material is not asbestos.

There is wiring that has asbestos such as the wiring used on old stage lights due to the heat. It is white and very obvious to anyone who knows, often people cover it in tape but there is still enough around with it exposed. Asbestos wiring insulation would probably fall apart if it was used for automotive purposes.

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1986 Mayfair (998 auto), 1974 S, 1974 Van, 1972 PMG Van

Too many minis

I understand it was cotton covered. I owned a 1961 850 in 1964.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

The Lucas documentation describes it as "fabric" treated for oil and water resistance. Just by looking at it, the fabric has been soaked in shellac or lacquer.

Thanks Dave

I’ve found a post here from Rodger Howard (gauge guru) with the following specs:
Early = 3 ohms empty, 83 ohms full
Stabilised = 250 ohms empty, 19 ohms full

viewtopic.php?f=2&t=88089&p=962830

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Timmy
You could try to jumper wire a resistor from the Green/Black connector to a good earth point in the boot as a substitute for the sender. Jaycar (and other electronics stores) sell 5 watt (white rectangular) resistors for about 70 cents each. Buy a few, 3.3 ohms, 22 ohms, 82 ohms and 220 ohms would cover both types of gauge and sender unit.
Remove the green/black wire from the sender lug and connect it through the resistor to the car body. If the gauge works ie 3.3 ohms => empty, for the early gauge, and 82 ohms => full, then your problem is at the tank end. If the gauge is still wrong, then start looking at that end.
Good Luck. Dave D
(Does the unstabalised gauge "sit" at full or empty when the engine is off?)

Thanks Dave

My sender and gauge appear to be working fine
Sender wire to earth (lowest resistance) is showing empty
Sender wire removed (highest resistance) is showing full
It shows empty with key off as there’s no power to the gauge end

I’m off to jaycar tomorrow to get some appropriate coloured wires & a relay and fuse for the fuel pump feed.

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