Having all sorts of issues with the Twin Fuel Pump Control Board, so I did the mature thing and threw it all out. Time to start again.
Simplified the whole idea, got rid of the op-amp, and I am just using a single MOSFET. Bench testing of a bread boarded prototype is showing promise.
I have some new boards on order which will be here in about 3 weeks. I have to order a new MOSFET as the ones I have don’t turn fully on until 15.5V which is too high, although they will do for testing purposes.
Stay tuned.