OK but keep the 5th injector on the pipe....as requires some pressure to pass Fuel through nossel, rather than free run in disconnected pipe, that's the pipe where full 85/90psi would be seen with Pump relay " Pink or Silver " with terminals 30 / 87 bridged....ive a feeling Fuel struggling to get through that Filter !!, you might be able to hear the 5th injector " Click " on test....over the noise of starter cranking may be ?. Peter