Fuel Pump Redux

[Cutlass]

As I've decided to convert to negative ground, I decided to check the AZX 1307 (pretty new, it seems) fuel pump, to make sure the expected diode was properly in place. Yes, I've read the prior posts on the issue. What I found was no apparent diode, but a capacitor instead. The pump bench tested fine, and was working when I started dismantling. So do I just replace the capacitor with the proper diode? Is there a picture of how this should look?

 

[Dave Russell]

The earlier SU pumps had a capacitor & weren't polarity sensitive. Somewhere along the way, they decided that a diode instead of a capacitor "might" be more effective at point arc suppression.

The later models with diode are polarity sensitive as you know. I believe some enterprising sellers discovered that the capacitor was nearly as effective as the diode & not polarity sensitive. This saves the trouble & expense of having to stock & deal with two different ground models of pump. A few less caring sellers just left out the diode & no capacitor to make a universal pump. The points won't last very long with no arc suppression.

I personally would just use the capacitor.

If you wish to convert to diode, just replace the capacitor with the appropriate diode. Moss # 377-135 for positive ground, or # 377-145 for negative ground.
D

 

[Keoke]

HI Cutlas, I have been depolarizing the SU pumps for years using a non polarity sensitive Mylar capacitor the pump will work just fine for you as it is.---Fwiw--Keoke

 

[Cutlass]

Thanks to both of you. Having read all the prior posts on the issue, I expected to see a capacitor and/or diode, but not a pump with no diode at all. The pump was installed by the po three years ago, just a few days before I bought the car. The pump looks new, and worked fine at disassembly. Guess I'll just put it back together and call it done.