Chris, I think I wasn't quite clear in my last post. What I intend to do is exactly what you laid out in your first reply. Stock pump positive wire will trigger the relay, which will feed the new pump with juice right from the battery. This way the new pump should go on and off like the stock pump, except for this 25% duty cycle. Personally I'm not worried about the 25% duty cycle since it is only supposed to occur when the engine is cranking. I have never needed more than three revolutions, at the most a second and a half of cranking on the coldest days until the engine starts, so having the pump run at full blast for that small amount of time isn't going to hurt anything I wouldn't think. What I meant when I mentioned the fluctuating voltage in the stock pump circuit is that I don't know if 8volts is enough to get a relay to kick on, I think it's going to work just fine. If you want to try it this way, get a heavy duty relay from your local autozone or pep boys or whatever. It will come with a diagram that shows which pins on the relay go to what. Also get a fuse holder to go between the battery and the new pump.