My 03 MCS sat in the garage for a week. It started normally but stalled immediately. After it stalled it wouldn't fire when cranking.
I checked:
- Spark checked ok.
- Compression checked ok.
- DTC's showed only -545454 which is all clear.

I gave it a shot of ether and it fired randomly but didn't start but since the throttle is drive by wire I couldn't be sure if it was open or not.
Connected a fuel pressure gauge and observed very little fuel leakage when I connected it.
Fuel pressure was 60 psig which is about what I would expect.
After I connected the fuel pressure gauge I noticed it would fire randomly so I kept cranking and it eventually started. Since then it has started normally.
My theory is that the fuel pressure leaked down and the fuel vaporized in the fuel rail. There isn't a return line to the tank which would clear the vapor so the vapor had to be cleared manually, which I inadvertently did when connecting the gauge. The subsequent cranking cleared the rest of the vapor.

 

Hi,

I am having a similar issue. I have an 02 MCS, left her for a week, came back and she cranks but does not start. I swapped the battery, (as it died, and the AAA guy said it was "past due") she still just cranks and cranks. could you let me know your thoughts? sounds like the same issue. The tool you used to pressurize the system, is that rentable