2000 Mercury 200EFI starts but won't run

[plangley]

I recently purchased a boat with a 2000 Mercury 200L EFI motor, Serial 0T105699.
The motor has good compression. 120psi all cylinders and fuel pressure measures in the low 30s when you crank it. The motor had good spark and would crank but not begin to start when I got it. I had a marine mechanic look at it and he told me the EFI module was bad, I sent it off to Simon Performance Technologies and they changed all the injector drivers. When I reinstalled the module, the motor would fire when the ingition switch was on but die as soon as you let off the ignition. I changed the ignition switch on the boat and it had not affect. I hooked up another mercury wiring harness to the motor and tried to start it directly from the battery, to exlcude the boat wiring. Still does the same thing. I purchased a manual for the motor online and it references a mercury switch during several of the test procedures but they provide no information as to where the mercury switch, if it indeed had one, would be located or what it would look like. I'm hoping someone here has had a similar issue and might have some answers.

[EuropeanAM]

You shouldn't have a Mercury switch on that one (though you might have some switches made by Mercury).

Need to check the fuel pressure and monitor it before starting, when it starts, and what if any change as it stalls.

[JOE54]

dont have one on that model , test for spark on all 6 , fuel pump runs ?????

[plangley]

Joe,
The fuel pump runs when you turn the ignition on. It shows low 30s for the fuel pressure. Oddly enough, I can never feel it run after the start cycle. Sounds like I need to hook the gauge to it and monitor it to see if it drops out and never recovers pressure.

[EuropeanAM]

That would certainly be wise.