I had the same problem a few years back with a Saito 90 twin in a cowled situation. I put a resistor in the circuit from the battery to the pump that slowed the pump motor to where it was pumping a lot slower than normal. Then added a switch to short out the resistor for high speed pumping. I would then use the high speed to fill the tank but as it approached full I would switch in the resistor and fill slowly till the tank was full. Solved my problem..........RJ