How to prevent power fluctuation


I'm pretty new to creating custom subs and I would like to ask for some help regarding (as the titile says) power fluctuation.
I've created two subs for singleplayer use, both of them having the same problem: As soon as the sub starts moving the power starts jumping between a grid load of 1700 and 4300, therefore overloading the junction boxes and the lights constantly flickering. I'm quite certain that the problem comes from the engine and/or the ballast pumps and I've tried different ways to prevent it from happening but had no success. I would be very thankful with any tips you can offer me regarding this.
I might have to upload the sub here to show how I wired everything but unfortunately I don't know how to do that.

I'm thanking everyone in advance for taking the time to help me.