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Re: [Mgs] MGA , no start, no spark

To: "W. David Houser" <>, "MGList List"
Subject: Re: [Mgs] MGA , no start, no spark
From: "Paul Hunt" <>
Date: Sun, 21 Mar 2010 14:33:49 -0000
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 spark out of coil....
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