On Sat, 28 Aug 2010 05:31:27 +0000, DoN. Nichols wrote:
On 2010-08-28, wrote:
On Fri, 27 Aug 2010 07:17:18 +0100, Ted Frater wrote:
....
Then theres the temporary faulty car starter problem. Best cure is to
have mans oldest tool handy, thump the starter a couple of times then
it will work fine all week. And dont forget to slam the hood down
well.This always helps.

Sounds like my old Mini. always had loose connections on the battery
in the trunk - as well as having an SU fuel pump. Jump in and turn on
the key. If no "tickety tick_ in the back corner, slam the door or get
out and kick the left rear tire to start the fuel pump, then get in and
push the starter button. If it didn't crank, slam the door again with
the starter button pushed. Or just reach out the window and slap it on
the flank good and hard and yell "giddy-up!!"

My MGAs had SU fuel pumps as well. If it quit on the road, the
trick to get gas to get to a safe place to start was to turn the
ignition key on and of several cycles (no steering lock so it was safe)
and this would pump enough fuel into the float bowls to drive for a
little while.

Then pull over, open the trunk and get out one half of the jack
rod, tilt the seats forward and remove the cover over the batteries (two
6V batteries, one on each side of the driveshaft), get back in, turn on
the ignition, and bring the end of the rod down smartly on the fuel pump
(behind the passenger's seat) and it would run for a while. Repeat as
needed until I could get to work or home, then climb under, unscrew the
nut securing the points cap, remove the bolts securing the toggle points
assembly, rotate a couple of turns to change the toggle point, and
reassemble. Fine for another year or so. :-) (I understand that they
later added a capacitor to reduce the burn rate on the points.)
....

According to http://www.mgexperience.net/article/su-fuel-pumps-101.html
(which at the outset says, "As you all know, SU stands for Skinners
Union"), "Originally ... the only [arc] suppressor used was a
swamping resistor, in the form of resistance wire wrapped around the
coil and attached in parallel with it. As stronger coils that draw
more current were employed, a 0.47 microfarad capacitor was added to
assist ... ... With the introduction of the AUF 300 and AZX series
pumps, the capacitor was replaced with a diode to work in conjunction
with the swamping resistor ... ... Finally, the all electronic pumps
were introduced, which replaced the points with a Hall effect circuit
to control the current flow in the coil. These pumps look and operate
the same as the points style pumps, complete with the familiar tic,
tic, tic sound, but there is no longer any problem with point wear".

Then the article goes on to list the seven "more common problems
with SU fuel pumps" (burned and/or sticking points, stiffened
diaphragm, leakage past valves, broken pedestal, various fuel
leaks around loose or cracked parts, air leak, clogged lines)
and explains how to fix them.

--
jiw