My 2003 Volkswagen Golf 2.0 will crank but not fire up(unless gas is poured directly into the throttle body). Got spark and fuel (up to the injectors) but when I checked the voltage to the injectors I only get 3.42v, I checked all the grounds I could find, fuses and relays that are related but nothing so far. Timing belt looks good, new battery and new fuel pump. Had a OBD2 reader on it and got codes like Injector circuit low, and injector circuit malfunction in cylinder 1, 2, 3, and 4.
Volkswagen Golf fuel injectors not firing
So you do have fuel pressure at the fuel rail? The Powertrain Control Module(PCM) has internal drivers that control the injectors. There is a Red/Violet positive wires. Check all the grounds in the pcm harness also. The pcm grounds out the injector circuit to fire the injectors. If there is a broken ground wire than the pcm won’t be able to ground the circuit. Get a digital multimeter and check all grounds in the harness for continuity to ground. If all are good than test continuity from all wires to pcm from injectors than check the wires for the cam and crank sensors. Also, a shorted O2 sensor can cause this problem. Unplug it and see if that makes a difference. Let me know if you need a wiring diagram.