Fuel consumption in a gasoline injection engine is determined by:

1) Injector flow
2) Fuel line pressure
3) How long the ECU opens them for (influenced by temperature sensor)

As you fitted new injectors you may want to check they are of the right type.
You should be able to get a fuel pressure gauge, or just renew the regulator if cheaper.

IMO the tank should not be pressurised, that might also force more fuel in - it should vent through the fuel cap IIRC.