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<p>These pumps are both equipped with a diode and both are thus
polarity sensitive. The difference is in the colour code of the
wiring of the diode. Red in one diode is black in the other. If
you have a negative earth pump you can use it on a positive earth
car if you change over the two wires of the diode and visa versa.
These are later SU-Burlen pumps, not original SU´s. They probably
have the taped plastic stepped caps instead of the Bakelite
cylindrical caps sealed by a rubber band and taped over by tape
with the SU logo. <br>
</p>
<p>The older SU AUF301 pumps usually have a capacitor, a
greyish/yellow cylindrical item with the the wires at both ends.
These pumps are not polarity sensitive. <br>
</p>
<p>I usually replace the diodes and capacitors by a transil, in fact
a 2-way Zener diode which is bipolar and limits the voltage across
the points to 18V, thus practically preventing sparking. These are
also not polarity sensitive.</p>
<p>The transil will cost you though, $0,10-$5!!!, depending on
quantity.<br>
</p>
<p>The AZX1307 is not the correct pump for the AH. The original on
later cars was AUF300 series, mostly 301 but there are some
variations. The replacement of the AUF301 is AZX1308 which
delivers a higher pressure, if my memory is correct 3,8psi versus
2,7psi</p>
<p>Kees Oudesluijs</p>
<p><br>
</p>
<p><br>
</p>
<p><br>
</p>
<div class="moz-cite-prefix">Op 23-6-2018 om 00:18 schreef
<a class="moz-txt-link-abbreviated" href="mailto:hspethmann@t-online.de">hspethmann@t-online.de</a>:<br>
</div>
<blockquote type="cite"
cite="mid:1529705897911.401922.b8f224fe3db279f943b926527275b72987cb6db9@spica.telekom.de">
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<title></title>
<p style="margin: 0px;"><span style="font-family:
arial,helvetica,sans-serif; font-size: 10pt; color: #000000;
text-decoration: none;">My Healey:</span></p>
<p style="margin: 0px;"><span style="font-family:
arial,helvetica,sans-serif; font-size: 10pt; color: #000000;
text-decoration: none;">BJ8 MKIII 1964</span></p>
<p style="margin: 0px;"><span style="font-family:
arial,helvetica,sans-serif; font-size: 10pt; color: #000000;
text-decoration: none;"># L27347</span></p>
<p style="margin: 0px;"><span style="font-family:
arial,helvetica,sans-serif; font-size: 10pt; color: #000000;
text-decoration: none;">pos. earth</span></p>
<p style="margin: 0px;"> </p>
<p style="margin: 0px;"><span style="font-family:
arial,helvetica,sans-serif; font-size: 10pt; color: #000000;
text-decoration: none;">Fuel pump for the last 20 years:</span></p>
<p style="margin: 0px;"><span style="font-family:
arial,helvetica,sans-serif; font-size: 10pt; color: #000000;
text-decoration: none;">SU AZX1307</span></p>
<p style="margin: 0px;"><span style="font-family:
arial,helvetica,sans-serif; font-size: 10pt; color: #000000;
text-decoration: none;">now with a slow, but steady clicking
every 15 to 20 sec , when ignition is on.</span></p>
<p style="margin: 0px;"> </p>
<p style="margin: 0px;"><span style="font-family:
arial,helvetica,sans-serif; font-size: 10pt; color: #000000;
text-decoration: none;">I thought, the easiest solution is to
change the pump with a spare pump I have in my trunk for about
the same time as the first one. Both pumps look the same on
the outside. Both pumps are wrapped in black tape. But the
label on the box of the spare pump says: AZX1307 neg. earth.
</span></p>
<p style="margin: 0px;"><span style="font-family:
arial,helvetica,sans-serif; font-size: 10pt; color: #000000;
text-decoration: none;">In the archives I found a very
instructive contribution by Steve Russel from Aug 2009. And it
ended with the words: "A picture would be worth a lot of words
right now."<br>
</span></p>
<p style="margin: 0px;"><span style="font-family:
arial,helvetica,sans-serif; font-size: 10pt; color: #000000;
text-decoration: none;"> So I removed the cap on both pumps to
see if there is any difference in the wiring and took a
picture, attached to this mail.. Both pumps look the same
inside. You see the old pump on the left, the new one on the
right. Under the cap you see a piece that looks like a
capacitor, labeled as BZX1013. But following the explanation
with terminal 1, 2 and 3 clockwise beginning with the power
input stud and ending with the internal ground terminal I
suppose the "capacitor" is a diode. But when there is no
difference in wiring between the old and the new pump, why
could it be, that the old one looking like a neg. earth ran 20
years in a car with pos. earth?<br>
</span></p>
<p style="margin: 0px;"><span style="font-family:
arial,helvetica,sans-serif; font-size: 10pt; color: #000000;
text-decoration: none;">I'm confused and hoping for your
wisdom to shed some light on the problem.</span></p>
<p style="margin: 0px;"> </p>
<p style="margin: 0px;"><span style="font-family:
arial,helvetica,sans-serif; font-size: 10pt; color: #000000;
text-decoration: none;">Best</span></p>
<p style="margin: 0px;"><span style="font-family:
arial,helvetica,sans-serif; font-size: 10pt; color: #000000;
text-decoration: none;">Achim</span></p>
<p style="margin: 0px;"> </p>
<br>
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