Troubleshooting theory: For the fuse to blow, a wire in the circuit that has plus voltage must contact a ground path OR there is excess voltage being drawn. Since the fuel pump is a constant draw device as is the ECU, logically the only cause left is a short.

Why only under heavy acceleration? This isolates the probable area of short to somewhere where the wires are between the engine and the body since that is the only place where the wires need to flex as the engine reacts to power input and traction resistance.

Looking at the engine while parked and NOT IN GEAR, have someone "blip" the accelerator to see which way the engine rotates when under load. Then look for the wire(s)that move the most. A wiring diagram would narrow your search since you are only concerned with wires that are connected to fuse number one.

After that it is the PITA examination of the individual wires that make up the bundle(s)in the areas that flex the most until the problem is found.

Once found, do not stop there. Why (If)is there so (too) much flex in the engine to body area? Bad engine and tranny mounts?

The blown fuse is a symptom, the cause is the short wherever it is found. The true problem is what caused the short to occur in the first place. Do not stop diagnoses once you have found the short. It may not be enough and it will return later and really drive you crazy since you will tend to not look at the same place having once eliminated it as the problem. Or the short will cause more than just a blown fuse next time it returns.

The other solution is to never accelerate hard enough to blow the fuse. That probably would not be feasable.

Duane