another fuel guage question

[mrclion]

I have a 1962 2 door the fuel guage reads back to front?

tried the sender unit from a 1970 2 door saloon and its the same?

any help appreciated

[Cam]

Do you mean full when empty and vice versa or do you mean it is trying to go left of the empty mark?

[mrclion]

yes full reads empty empty reads full

[Cam]

Check all the earth connections (especially to the speedo and surrounding body).

If you have a test meter, then check the output of the regulator on the back of the speedo (the wire that goes from the gauge up to the regulator box) it should be 12 volts ish.

Then check the resistance of the sender unit (higher resistance value when empty than full).

Then check the continuity between the tank sender to gauge wire and check it is not shorting somewhere.

Lastly remove the fuel gauge and test it by applying power to one contact (the regulator one) and shorting the other to earth. It should deflect quickly to full.

[57traveller]

Not the answer to your problem because your reading was incorrect originally, but the 1970 sender unit may not be compatible with your gauge. Does your car have bronze speedo head without voltage stabiliser?
I'm sure there are differing sender units - the 1970 will be for the later speedo with a voltage stabiliser. I don't know if there is a visible difference because I've only seen the older version "in the flesh."
The older type are only available 2nd hand.

[Willie]

If you do have the bronze faced speedo then the later
type of tank sender unit will NOT work, you must obtain
the unit from the same type of Minor. Both types will
fit the tank without problems. A useful check is on the
type of connectors used on the tank sender unit...if they
are of the Lucar push on type then that is a late type
unit, if they are secured by nuts it is an earlier unit.

[mrclion]

looks like someone has fitted the later sender unit before I got the car then its a lucar connection

yes the speedo head is bronze

can the speedo head (black) and sender unit from the 1970 be fitted as a replacement and would it work?

[Willie]

I depends, if your car is a 948cc model then the black
faced speedo' will not work accurately because it is
calibrated for a different rear axle ratio. The trouble
is that the earliest 1098 cars ALSO had bronze faced
speedos(until 1964). Is your car 948 or 1098?
If it is 1098 then the engine number will start with 10MA.
Is the gearbox casing smooth or ribbed?

[mrclion]

GEARBOX IS RIBBED AND ENGINE NO IS H69638

ME THINKS ITS A 948CC

[Gareth]

Ribbed Gb would be a 1098 unit, but the rear axle would hold the key to this problem, perhaps...

The earliest 1098's had, I think different innards to the speedos, didn't they, otherwise they wouldn't work. Trouble is, I don't think you can distinguish between the early and late gold speedos from their outward appearance... can you?

[57traveller]

The early 1098's with a bronze speedo would have a higher ratio diff so would assume the speedo would be calibrated for this change. The number on the speedo dial would give a clue to this but don't know the difference in these numbers.

[Willie]

As stated you have the 1098 gear box if it is ribbed!! I
don't think it is common to find the 948 engine with the
later gearbox so ...is that the full engine number because
it is missing the most important part which are the prefix
numbers! For example, a normal 1098 engine would
read 10MA-U-H followed by the number. A second check
is to look on the manifold side, just behind the front
engine mounting, below the manifold,on the side of the
crankcase. You may see a flat area with '1100'on it.
The engine number you have quoted tells us that it is
high compression but nothing else! Look at your
log book. In addition, there is a number on the face
of your speedo as '57' says this number will tell us
which rear axle ratio it is calibrated for, so give that
number please.

[mrclion]

might have gave you a bum steer here guys the engine no is as stated but have a 1970 spares car which I removed the engine and gearbox last week, will have to check tomorrow to be sure? maybe its that that is ribbed

will get back tomorrow

thanks

[Willie]

Here is another way to check... the final CHASSIS number
for the 2 door 948 Minor was 990288 so if yours is higher
than that it should be a 1098.

[mrclion]

havnt had time to check the box yet my engine no starts with 10? but not m

chassis no is mia255d997882

no on speedo is sn4477/30 1375
but have no way of knowing if this is authentic

both back axles look the same ie same filler holes
front drums are the same size

[Willie]

Crikey I think we need inspector Frost on this!!
If engine number starts with 10 then it must be
a 1098. Your speedo number is not listed but
SN4477/80 bronze, is shown as speedo for 2 doors
with chassis numbers 990290 to 1082279. These
are 1098 and your chassis number is in that lot.
The normal chassis number for your car would begin
with M/A2S5 Have you read it correctly? that is 'S' 5
not 55. No engine was ever designated as just 10,
there was always a letter afterwards.

[mrclion]

definately ribbed same as 1970 1098 spares motor

[mrclion]

sorry willie missed the second page before i posted the above

[Willie]

mrclion.....did your gauge ever work correctly or has the
fault developed? I have done a thorough test today on
the sender unit from a bronze faced 1957 speedo and, to
my surprise it reads almost a full short to chassis on EMPTY
(float=down) and a high resistance on FULL(float=UP). What I
need is for someone with a spare late type(Lucar connection)
sender to test it to see if it reads almost a full short between
the terminal and the housing on FULL(float =UP) i.e. the exact
reverse. Any one out there with a spare and a meter???

[mrclion]

no my guage has never worked properly it has read like this since I got the car thats why I cant prove if I have the correct float or speedo.

I have tested both sender units by proving the guage first of all ie. hold the terminal to earth and it goes to full, just the same as with the float connected. if I remove the float and earth the casing to the body the guage reades full when the float is down and as I lift the float it moves towards empty.