I've been trying to figure this out for some time now, my AYC pump causes a large voltage oscillation when its pumping. (it always pumps after 50% throttle or so and turns on even in straight line) The voltage oscillation causes my dash lights to flicker/dim and my AFR goes up and down because the injectors areing seeing linear voltage at WOT. There have been a few others with the same problem on here but it never came to a conclusion. Another thing i noticed is when i have the engine off and ignition on and i step on the throttle, the AYC pump keeps pumping and never shuts off. Here is a thread with the same electrical problem.
Any help is greatly appreciated!