A fuel injector assembly for an emissions-based EMD 710 locomotive dieselengine. The fuel injector assembly includes a needle slidably positioned within a bore of a valve body of the injector assembly, where fuel pressure introduced into a bore chamber causes the needle to open a spray tip. A spring mounted within the bore forces the needle to close the spray tip when the fuel is not being applied. The spring is a dead coil spring including inactive coils where at least portions of the coils at both ends of the spring are in intimate contact with each other so as to reduce spring wear during operation of the assembly. Because the dead coil spring has reduced wear, the VOP set point of the fuel injector assembly can be reduced, which reduces NOx emissions.