'Early' (including my 73) pumps had capacitor quenching which is not
polarity sensitive. At some point (reputedly in 1977 when the
identification changed to AZXnnnn) diode quenching was introduced which *is*
polarity sensitive and incorrect connection will result in damaged wiring
and/or a blown diode. If the diode blows it will stop any further damage to
the wiring, the pump should operate, but the contacts will burn. AZX pumps
are available in negative and positive ground configurations, the
positive-ground electrics end is sealed with red tape and negative ground
with black. Having said that it is a relatively easy matter to reverse the
diode and hence reverse the polarity of the pump, definitely a better idea
than reversing the wiring to the pump itself. Square riggers had pumps with
no quenching and it was part of the routine maintenance schedule to remove
and clean or replace the contacts. Good job the pumps were accessible.
----- Original Message -----
From: <mg-dennis@mindspring.com>
To: "Max Heim" <mvheim@attbi.com>
Cc: "MG List" <mgs@autox.team.net>
Sent: Friday, August 09, 2002 1:58 AM
Subject: Re: Positive ground fuel pump
> When I converted my B to negative some 10 or so years ago I dont remember
doing
> anything to the pump. It's been supplying fuel ever since. So you may be
right
> in that early pumps are not polarity sensitive.
>
> Dennis Cox
> 67 MGB
>
> Max Heim wrote:
>
> > No, I was talking about the description of "how to convert [the car]
from
> > positive ground to negative ground". It actually claims that original
pre-68
> > fuel pumps are not polarity sensitive, but I recall that mine did not
work
> > until I switched the leads. Whether that causes an electrical hazard is
not
> > addressed.
/// or try http://www.team.net/cgi-bin/majorcool
/// Archives at http://www.team.net/archive
|