Here's the situation...my 1970 1.7 with FI will only start if I disconnect the MPS vacuum hose. The engine was running rich, I checked the old MPS (didn't hold a vacuum) so I replaced it.

The only way I can start the car now is to disconnect the vacuum hose from the MPS (puts the car in the same scenario as when the broken MPS was on) and it runs rich. As the car is running, I reconnect hose to the new MPS and the car dies out. There is definately vacuum pulling from the hose. I'm guessing that the MPS is sensing the vacuum, adjusting (leaning) the mixture appropriately, and the car stalls.

I've check and adjusted the fuel pressure.

Any ideas?

if you need the engine to have full rich on to start and run it something is wrong maybe the CHT? Check that first....