I am assembling a fuel system now and am going to use a SSR triggered by a ECU to PWM power a brushed fuel pump (AEM 400). This is for the usual reason of varying pump output based on load to keep the fuel cooler.

Somewhere, I believe it was on ls1tech, there was a discussion about running the PWM frequency at around 100 Hz (to prevent problems at higher frequencies). Someone mentioned their pump was 'noisy' but they made it quieter by adding a capacitor, maybe 10 uF, across the +/- of the pump power lugs.

So, is this common practice more or less, and if so, how does one arrive at a good value for the capacitor? Start small, increase size until the noise is bearable? Diminishing returns at some point? Do not go HUGE like 1F because that could cause an inrush current issue?

I looked awhile here and on google and for some reason could not find it again. My google-fu is weak today.

Thanks

 

Hopefully someone will be able to give you some good feedback on this. Most (car) people I talk to dont understand pwm in the first place.

They think the fuel controller on my car is some sort of magic device that costs too much.

 

https://ls1tech.com/forums/pcm-diagn...fuel-pump.html