[Healeys] Fuel pump polarity

[Bob Spidell]

Is the "something which resembles a small condenser across the points" a small plastic cylinder with red and black leads (wires coming out of it) at one end? If so, it's a diode--don't ask me why it's 20 times larger than it needs to be--and if the red lead goes to the screw which secures the base of the flexible points--the Y-shaped piece of spring steel--then the pump is rigged for positive ground. If the black lead goes to the base of the points it's negative ground. 

If it's a cylindrical piece with wire leads out of each end it's a capacitor--aka "condenser"--generally used on middle-series pumps (diodes came on later pumps, early pumps had no arcing protection). I'm not positive (pun?), but I think the capacitors as used on some of the pumps are electrolytic, which are definitely polarity sensitive. Are there any markings on it? If it's an electrolytic there may be '+' and '-' markings on the ends; again, the terminal which connects to the base of the points is the (ground or 'common') polarity. If so, the leads can be swapped to reverse polarity. 

Have heard it might help to polarize the solenoid--similar to polarizing the generator when changing to negative ground--by momentarily connecting a power source to the correct leads, but I suspect it's not necessary as the first current pulse will do that anyway. 

Some googlin' turned up indications the AUF301 was originally positive-ground, but the polarity could have been changed. If you can send me a (closeup) photo I might be able to help a bit more. 

Some useful info here: http://www.mgb-stuff.org.uk/fueltext.htm 

Bob 


-------------------------------- 
Bob Spidell - San Jose, CA 

----- Original Message -----


I have an AUF301 SU pump on the bench. Old, but looks serviceable with new 
points and a bit of tlc. 

How can I determine its polarity? (I'm not sure where it came from or when). 

It's not electronic(!) and has - I'm hopeless with electronic terminology - 
something which resembles a small condenser across the points. There is no 
obvious left or right/pos or neg appearance to this thing....looks like it 
goes on either way. 

Any ideas? 

Simon