anytime a fuse blows, you usually have a short(unwanted path) to ground meaning that more current than that circuit is designed for is coming across that fuse. A mechanical resistance on the load(pump) part of the circuit can do the same thing. The ecu cant do it because its on the ground side.All it does is provide a path to ground I would check wiring form the realy back to the pump and sending unit and check voltage at the realy first . You should have 12 volts at pin 30. Look at wire size,corrosion, loose contacts. Too big of a gauge of wire will draw more amps. Make sure the wires arent contacting metal some how. (A screw through the ground wire, a pinch in the wire to the frame.If you have an ohm meter take a resistance measurement at the fuse while its cold and then when it blows another fuse take another one while its hot. The reading shouldnt change. If it goes up when its hot, I would start with all connections from there back. You may just have a loose connection at the pump or sending unit. If you drop the tank, take an ohms reading across the pump. I dont remember what the spec is but im sure you can find it here. If its above that spec then your pumps going bad.
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