Follow the wiring diagram backward from the pump.
Make sure you have full power at the white/purple wire at the Fuel Pump Relay (FPR). Also make sure you have a GOOD ground/earth at the black wire at the FPR.
If they test OK, then the FPR is bad and not allowing full voltage. It is the same as the Fog Lamp or Horns (mini) relay , so you could swap them and see if that helps.
The relay location diagram is on PDF page 11 in the V6 Electrical Manual found at http://www.lotusm100.com/manuals. The wiring diagram is on PDF page 67
If the ECM feed is damaged, then the relay won't trigger, so you need to use the volt meter to make sure the relay winding (pin 1) is getting the full 12V when the ECM is trying to make the FPR run. Pin 2 is the ground/earth.
You could also remove the relay and run a jumper wire between sockets 3 and 5 while starting the car as it will bypass the ECM control of the fuel flow.
DON'T drive the car with a jumper. The pump will keep running and will at the very least drain the battery, but you don't want to over-heat the pump either.
