Mark,
the tandem pump fuel pressure at idle should be 3 - 4bar, rising to 9 bar at wide open throttle.

Off memory, the in tank pump should produce 0.5 - 1 bar, but I don't have the exact spec here, however the ones I have seen that can't maintain this provide a decidedly dodgy, non uniform scope pattern.

Frank Massey tests the pressures on one of these here, in the pump duse vibration chapter - if you have a spare 25 minutes.
The Tandem Pump was completely shot, no pressure from it at all, but the engine still started & idled satisfactorily.

http://content.yudu.com/A1dxye/AI-2/resources/index.htm?referrerUrl=

If the in tank pump fails, the Tandem pump cannot generate a supply of fuel to the injectors - the engine cranks / won't start as a result.

The vac operated engine shut off flap in the EGR housing is prone to gumming with a large build up of sludge - these can stick shut, causing a none start.

Starter speed should be 300RPM > on a hot engine.

Coolant Temp Sender reading correctly - these run ropey when the CTS is off the scale.

Jon.