Hey everyone. I am interesting in using my PMU to control the duty of my Walbro 485 lift pump. Currently the PMU simply turns it on. This pump feeds a surge tank which contains a speed controlled Fuelab pump. My issue is that the 485 supplies more fuel than needed for idle and light loads so I want to use the PMU to duty it via PWM. I am not clear if this ideal to do directly with the PMU. It seems like being able to use higher frequencies, closer to 1000Hz is better but the PMU output appears limited to 400Hz max. I see people suggest a flyback diode, others do not.
So - can I safely and effectively duty this pump directly from the PMU at 400Hz? Should I use a flyback diode or is that not necessary?
Thanks