I remember reading some stories, can't recall what threads, of problems with the electrical connectors back by the pump that caused issues with some aftermarket pumps and low flow rates. Seems that poor connections weren't letting enough current get to the pump and so low flow rates. It is entirely possible that a bad connection can cause excessive current drain which would blow your fuse.
Inspect the wiring and clean and dirt or corrosion, replace connectors as necessary. You may need to pull the fuel pump and inspect the connections inside the tank as well, if there is corrosion there, replace as well. Once the bad connections are fixed up, you should be good.
Do NOT put a larger fuse in there, that's only going to cause something else to blow to protect the beefier fuse. You'll melt wiring, blow relays, or worse.