Hi,
Thanks for deleting the duplicated post, sorry 
And thanks for the fast response, well I thought about switching pumps ON and OFF, but I will have problems with the tune, my aftermarket ECU can set two tuning maps, I already used the two maps, one map for the gasoline fuel, and the other map for the 100% alcohol fuel, so it will be bad idea to switch OFF 1 or 2 pumps while I have a tune with 3 pumps, as the car is used in illegal street drag races, so it will see cruising from home to racing and then race.
What is the best brand and price for the motor control board that you recommend? I have seen now some boards from 15$ to 80$! so am not sure!
Other thing can't I make the Aurdino to control the stock automotive relays? I have checked the Bosch and Siemens style relays it seems the 5V from the Aurdino can't activate the relay coil and deliver power to the other pin relays, how I can do this? it seems there is no much information about doing this!!
Thanks,