Electrical problem
 

When I turn my fans off and on, I hear it in my fuel pump. Can anybody tell what that is??

Power surge ?

Voltage drop due to undersized electrical system ?

Do your headlights also dim when you do this ?

EDIT:
You could add a capacitor like they do in high draw stereo system to help with the surge ?

I have twin fans which used to come on at same time with the same results as you, and now running a Davies Craig controller that turn on one at a time....much less draw at one time.

I think I found it Doug, I drilled and tap my water pump and the temperature sensor wasn’t getting a good ground coming from the relay. So i added a second ground to the frame. Lights do not dim anymore.Thankyou for the feed back.

I still have issues. Working everything out one at at time. I drove it yesterday. Have good throttle response, but when I’m cruising about 35 or 40. I get a exhaust backfire and my AFR reading like 15.7. I know that’s lean. So I’ll change the jets and see what happen.

15.7 at cruise isn't terrible.

Could be an exhaust leak. Torque the header bolts.

My fuel pump changes pitch when the blinkers blink.