You can control a 2nd fuel pump with the JB4, unless you are using the extra JB4 high current output for the 2STEP/NLS relay, in which case then you need a Hobbs switch. We'll be adding a high current output to the BMS PI controller at some point soon to trigger a second pump. We need it to trigger the meth pumps for direct injection meth anyway.
I assume you mean port injected meth?