Hi Desmond,
In general I do not suspect the regulator according to the described
symptoms.
Though by attaching a normal (not digital voltmeter) to the output of the
regulator, you can check, that this output varies.
The voltmeter needle should move regulary.
Be sure, that the housing of the regulator is truly connected to the
firewall. This is part of the electrical circuit!
#1
This may happen after replacing the sender unit, or when the sender unit
has become faulty.
Quick check for this is losen the sender unit wire. Make this wire connected
to ground for a few seconds.
This should move the instrument to full position.
! Warning do this not for a long time, as you will toast the instrument!
Just a few seconds.
When a full swing of the gauge is achieved by this, the sender unit is
faulty.
Get the fuel tank emptied and replace it. Manuals display how to do - not
difficult.
If the gauge still does not reach the end, either a wire misconnection has
occurred or the instrument is faulty.
The list archive may help for a good address to fix.
Beware, that after replacing the sender unit, the gauge must be calibrated
to its max and minus positions.
Two screw holes at the rear side of the instrument are used to get this
done.
#2
This appears to be a connection not always working well.
Check the spade connector linked to the temp. feeler on the engine block.
This feeler tends to fail sometimes.
Again temporarely shortening this spade connector to ground should move the
instrument4indicator quickly.
! Warning do this not for a long time, as you will toast the instrument!
Just a few seconds.
Check above points of the regulator, but if that is faulty, the fuel
indicator should fail at the same time...
If this all did not solve it, you should follow the electrical circuit. A
proper diagram of the correct year MGB certainly will help.
Replacing the temp sender on the engine may be a bit tough job to do.
I had to use a ring wrench and put my full wight onto the wrench, before the
old sender came out!
25+ years had made it solid tight to the block.
Good troubleshooting!
Cheers,
Hans
1971 BGT
----- Original Message -----
From: "Desmond Mullen" <dkmullen@email.unc.edu>
To: "MG List" <mgs@autox.team.net>
Sent: Tuesday, October 03, 2006 10:27 PM
Subject: Voltage regulator, gas/temp gauge question...
> Hello y'all,
>
> I wonder if these two items are related:
>
> #1) The gas gauge on my rubber-bumper B never reads full when I fill up
> the
> tank - the gauge tops out at about 3/4 full.
>
> #2) The temperature gauge occasionally does not register any temperature.
> At
> some point later it may jump up to where the temperature really is. The
> engine seems to be operating and cooling itself normally (and the fans
> kick-in as appropriate), but it occasionally doesn't read on the gauge.
>
> Could these problems together add up to a voltage regulator problem? Or
> where else should I look? Neither issue is a very big deal - it's just not
> quite right.
>
> Thanks in advance!
>
> -Desmond
> '78 MGB (daily driver!)
> --
> ----------------------------------------------------------
> Desmond Mullen dkm@unc.edu P:919/843-7998 F:919/962-1238
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