is adding a TVS diode to SU fuel pump thats has capacitors worthwhile ?
for $6 a pack of 10 30V TVS diodes, will it help preserve the life of my points
They are AUF303 in 420G. there a 2 of them and they have given very little problem after more than 20 years, and do have capacitors in them, but if it helps, I will do it
It’s not the voltage going through the points that is the problem, it’s the current.
If you want, you can fit an electronic module that runs the pump either without a points cradle, like Burlen do, or you can use the points cradle to make a transistor do the switching, like I do. See the classifield section for more details. Either of those keeps the high currents away from the points cradle and protects against transient high voltage spikes.
What the capacitor does is take a short time to charge and discharge whenever the points close/open, so it takes the edge off of current inrush, thus helping the points not to arc.
A TVS diode protects from overvoltage, so is only useful for removing the electrical noise associated with flyback voltage every time the points in the pump disconnect. This type of residual voltage spike typically affects other electronics, of which there is very little or none in an old car like this.
kind regards
Marek