Absolutely run a relay and proper fuse. Also, don't run the the fuel pump load through the inertia switch. Use the key on for 12v trigger to the relay and inertia switch to kill the ground to the relay in case it's tripped.

rpm wrote:

Thanks guys! Ya, I do have the inertia switch mounted to the deck lid hinge support. My fuel pump 12v comes from a buss bar to a hidden switch in the cabin, then back to the pump.

Werze-it-hid-at?!
6s6
 

6sally6 wrote:

Werze-it-hid-at?!
6s6
 

I'll show ya mine Sally, if you show me yours.
 

Bob, absolutely use a relay for several reasons. One it takes the load off the control wiring. Another reason, if you didn’t the length of the wire supplying power would have to be much longer. More expense and more importantly voltage drop. The more fuel the pumped, the more amperage needed and the more voltage drop.

What you want to do is take the distance X 2 and multiple that by the maximum amp draw, that will tell you the voltage lost on the wiring. Even though you’re running 1 wire, the steel has resistance too. To be safe I would double the distance which is how you would normally do it. So if the length of the wire is 15’, double that for 30’. #10 wire has .001 ohm per foot or .030 ohms resistance for 30’ for .6 volts lost assuming a 20 amp load. .6V/12V = 5% loss of voltage to pump. I would like to see no more then a 3% loss of voltage to the pump. If you’re pump doesn’t have enough power you possibly could go lean under some conditions.

Last edited by Huskinhano (1/16/2019 8:04 AM)