SU fuel pump circuit breaker spark

[Jaguar12]

Hello forum,

I have a working SU pump AZX 1307 with mechanical contacts. I have tried 2 varistors of the same type and an original capacitor and the spark intensity seems to be the same as per the foto.
I wonder if anybody can tell me if the spark I see is normal.

Greetings
Daniel

[Jack the lad]

Hi Daniel, the blue device should be a capacitor, its job is to arrest the spark as on your contacts for the ignition points. Are there any words/letters/numbers on it? which may help identification, or do you have the original. Some capacitors (tantalum) do look like your photo. cheers John.

[mgcjag]

Convert it to electronic....a member here on the forum sells a small circuit board that fits in easily.....search for Marek.....Steve viewtopic.php?f=7&t=15667&p=174267&hilit=Marek#p174267

[Jaguar12]

John, Steve,

Thanks for your input.
I am pretty sure the blue component is a varistor (no markings on it) which came from Burlen some time ago and it is dual polarity. I would like to keep it this way since as my spare, this pump should work on pos. and neg. earth.
As for the spark, it went away after I thoroughly cleaned all the terminals and contacts. So to answer my question: No , there shouldn’t be a spark easily visible.

Greetings
Daniel

[johnetype]

Varistor or capacitor, both will do a similar job in this application. If you were to use a large non polarised capacitor such as those across the input to a power supply your pump would remain polarity insensitive.

A capacitor would be a better choice for suppressing RF radiation so would be my choice for this application.

In reality, both in parallel would cover all bases.