Check voltage on the 12v supply to the coil with the points both open *and*
closed. If you have a bad connection back through the 12v supply you could
well see 12v with the points open, but zero with them closed, should be 12v
all the time.
Check voltage on the distributor terminal of the coil in the same way, this
time look for 12v with the points open and there *should* be zero volts with
them closed. If 12v all the time the connection through to the points and
the distributor body is open-circuit. Could be the points contact surfaces
high resistance, or open circuits in any of the wires, the very flexible
ones under the cap are designed to cope with the continual twisting of the
points plate under changing vacuum but do eventually fail. Test on the
distributor spade, points moving and fixed contacts, and points plate to see
where 12v changes to no 12v.
If zero volts all the time remove the wire coming from the distributor from
the coil and test the coil terminal again. If you see 12v now the points
are shorted out somehow, either no gap or the condenser has failed, or maybe
a wire shorting.
If you still see no 12v at the coil, and it is definitely on the other coil
terminal, the coil is bad. Older design coils *do* fail, they have riveted
spades which work loose and go open-circuit, and the fault symptoms can come
and go (BT, DT). Later coils have studs and nuts.
----- Original Message -----
> Car is pos. ground...replaced coil, no change.....switch on, fuel pump
> works, lights, getting gas...no spark out of coil....
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