When rewiring the fuel pump, is it vital that you keep the resistor box inline? Is it possible to just run an ignition-switched relay, with 10 gauge wire from the battery to the relay to the pump?

 

Yeah, as long as it is fused, and relay'd off the ignition wires, you should be fine.

The resistor is really only for increased gas mileage in non-WOT situations

 

Why is that though? What if the resistor pack fails and the fuel pump gets ***-tacular voltage? Wouldnt that suck? Shouldnt the injectors control the amount of fuel they put out? I'm getting an SAFC 2 (with the dial) anyway, so i can possibly tune the injectors down at idle.

I know in dsms the pumps receive a constant voltage through the method described above. And even stock, they SHOULD have a constant voltage.

 

I can't remember anyone ever posting about that happening to them. I guess it's always a possibility but is seems to be a very reliable system. The only component likely to fail is the relay, but it's not likely. Injectors don't control anything, they are an output device. The ECU say's when they open and close. The ECU also decides when to drop fuel pump voltage. This has all been allowed for in the programming of the ECU. Why do you think that? There's nothing wrong with the method Mazda used. At light load and idle there's no need for full fuel pump pressure becuae the amount of fuel required is tiny. As soon as any load is applied the pump voltage is increased.

 

If the resistor fails (and resistors normally fail open, not shorted) then the most the fuel pump is going to see is about 13.8V from the alternator. Not a problem.