Hi,
Can someone please tell me what the black square thing is on the fuel pump wire ?
Hope to hear from someone soon.
Thanks and regards ! ~ Denzil

What is the black thing on the fuel pump wire ?

 

Noise suppressor , not on all X308s from my understanding

 

Yes, and I am unsure how well it works.

 

I'd guess a cap across the wires, like you used to fit to alternators when you put a radio in your car?

 

Yes...I remember those. I also remember the squeal noise the engine made
on the radio when it was not done correctly.

 

There is a capacitor test with a simple meter

You would put the meter on resistance scale and as the Cap is being charged up by the meter the resistance will climb until the Cap discharges and goes back to lower resistance repeating the cycle

To know that the noise suppressor is working as installed , tune the stereo to an AM station , a bad noise suppressor will have AM stereo noise changing with engine / alternator RPM