I have dual Racor filters for each engine. Whenever the boat is serviced the technician leaves the valve so fuel flows through both filters. You can select either or both filters. I thought the idea behin a dual filter setup was so that you run on one and if it gets clogged/fouled you can switch to the other. I wouldn't think the engines require both filters from a consumption/flow standpoint. So my question is, should it be on both filters or one at a time?? Or am I missing something? Diesel, I know you will have the answer to this! Thanks in advance..