If the fuel pump runs and sends fuel to the fuel injector rail but no fuel is getting into the engine then the injectors are not being triggered to fire by the computer in your car. You need to do some basic diagnostic tests. Check wiring ect..... You definitely need good instructions and illustrations to tackle replacing the heater core on a car. Autozone have some popular workshop manuals for free on line once you register (for free) on their website http://bit.ly/autozone_repair_info .There is a company that independent auto repair shops "buy" their information from that offer a very reasonable service to do it yourselvers. You get a one year subscription to year make and model specific repair procedures, service bulletins, component locations, wiring diagrams ect.... great quality information same as the professionals have ,much better than generic workshop manuals from parts stores, much cheaper than the factory manual. http://bit.ly/alldata_repair_manuals or try http://bit.ly/mitchell_repair_manuals_online and get an online repair manual subscription.