The "cold start injector" serves more like a choke. When the engine is cold, it sprays fuel to enrich the mixture. You still need the other 8 injectors functioning to start the engine.

Cracking the fuel lines tells you nothing about pressure. You need to connect a fuel pressure gauge (google for that information) and see what kind of pressure you actually have.

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]