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Re: Bad Short Hunting

To: <Kf6alc@aol.com>, <mgs@autox.team.net>
Subject: Re: Bad Short Hunting
From: "Paul Hunt" <paul.hunt1@virgin.net>
Date: Mon, 29 Mar 1999 19:58:50 +0100
I think your diagnosis of the white being shorted to ground is flawed.  If
it were shorted it would have burned out by now, and possibly your ignition
switch and brown circuit with it.

If you look for continuity to ground on the fuse block you will always see
it on the top three fuses, simply because they have loads (coil and fuel
pump, side lights) connected to them.  The bottom fuse will also have
continuity to ground if things like the doors or boot lid are open.  These
kinds of loads have resistances of just a few ohms and you are wasting your
time looking for shorts with a hobbyists ohm-meter.

First thing is, as has already been suggested, try tapping the fuel pump
either sharply with the handle of a screwdriver or more gently with a small
hammer.  If that doesn't work you may have a disconnection.  Check for 12v
right at the fuel pump.  If you have no 12v on the white you have a
disconnection back towards the ignition.  If you have 12v on the body of the
pump you have a disconnection in the ground, this goes back to the rear
panel of the boot.

PaulH.
http://freespace.virgin.net/paul.hunt1/



-----Original Message-----
From: Kf6alc@aol.com <Kf6alc@aol.com>
To: mgs@autox.team.net <mgs@autox.team.net>
Date: 26 March 1999 00:09
Subject: Bad Short Hunting


>Thanks to all for the info on the Twin 6 / 12v exchange, but I still
couldn't
>start her up.  She ran for a few seconds while the starter fluid was in the
>carb, but then quit.  I seem to be having fuel delivery problems, so I was
>trying to check the pump.  I tried to disconnect the fuel hose at the carb,
>and nothing squirted, so I went back to the pump, and could not hear any
noise
>as I turned the key on.  I checked the wires, and the white wire seems to
be
>shorted to ground.  I went up to the fuses in under the bonnet, and to my
>surprise, EVERY fuse, whether connected or not, had continuity to the
engine
>block.  So, how do I track down a short when I don't even know where to
begin?
>Is there any good procedure for eliminating systems?  I just got her this
past
>weekend, so I know nothing about her, other than she had a history of
draining
>the batteries every 2 days or so.  I checked (with battery out, key off and
>out) across the positive battery cable to the negative, and read about half
>the scale on my multimeter at 1k ohms.  Isn't this bad?  I don't even know
>where to begin...
>Any hints are greatly appreciated!
>Greg 71B


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