[AlexMello401]

I recently installed a Toce exhaust and got my ecu flashed for my Yamaha YZF-R3 and now it’s popping the ignition fuse and I tried changing it and it pops instantly. What causes that. NEED HELP.

 

[NinjaBraap]

Well neither of those should blow a fuse of any type. Might have a wire grounding out that's been damaged.

 

[airhead83]

When the bike is running properly, then suddenly has problems after doing some other type of repair, chances are the 'new problem' was self-induced.
I'm guessing the battery and/or other wiring were either disconnected, moved aside, or somehow disturbed while doing your upgrades.

 

[kwillmorth]

ECU is likely blown. The ignition fuse feeds it and other loads. If the only change made was a reflash, and since re- installation, the bike blows that fuse, and has not run on the modified ECU, it's the ECU, or the ECU plug/connector. Look at the ECU pins to insure none are bent, double check the plug to insure nothing is shorted. If good, the ECU itself is blown.