When you first press the start button there is a sequence of starting procedure. How long are you holding the button down? The rapid clicking is the fuel pump priming the system; continue to hold the button down and let the glow plugs do their job and the sensors read the temp. The generator will not start to turn over until all of these conditions have had time to complete. The colder the weather, the longer it will take before the generator starts. If at this point the engine is sluggish or won't turn over you should follow Paul's advice.
Mike, RVIA & RVSA Certified Master RV Technician
Amy, Dr. Assistant - Roxie & Mei Ling, four legs each
2000 Gulf Stream Scenic Cruiser 450 hp & 1330# torque
06 Saturn Vue, 06 Chevy Z71 4x4 & 2014 Corvette Z51 M7