Should be able to inject power at the fuse prongs. First have some one prime the pump and see which prong goes to the pump, and which one is the power. Once you determined the prong going to the pump inject power and start the car. Also the codes are not related to the fuel pump. 21 is for an o2 sensor, but this could be caused by the fuel issue your already having. Do you have an injector pigtail tester, or can you get one? It has a light on it and blinks with the injector pulse. You can also use a your basic light up power tester. Make sure you are getting injector pulse.