2003 620 won't start despite have fuel pressure and spark

[808Ducati]

was running poorly at low rpms so took it into shop.  they said that I had a bad coil and that the drain hole in fuel cap was clogged and that I had water in my fuel.  They tested compression (good) and put in new plugs.
I drained the tank, cleaned it up, and refilled it.  I also changed the fuel filter.
I changed the bad coil - I now have good spark at both plugs.
Now the bike wouldn't start at all.
Tested the fuel pressure - 50 PSI coming out of the tank (after the filter).
I replaced the injectors and the fuel regulator (just in case) but still no start.
Here's the weird thing to me - the bike starts when I spray starter fluid into the air intake and runs fine (for a few seconds of course).
Now I'm stumped. 
Any ideas?
To double check, the fuel line running out of the bottom of the tank (in which I tested the pressure at 50 PSI) goes into the side of the regulator, out the bottom of it, then thru the two injectors and back into the tank, correct?
Help is appreciated.
Thanks

[ducpainter]

I'm not positive, but I think 50 psi is low.

Try clamping off the return line and see if it will start.

If it does it's probably a bad pressure regulator

[808Ducati]

thanks but I did both already - blocked off the fuel line after the injectors and installed a new fuel pressure regulator and  no luck.  I had researched that 45-50 PSI was correct - but I could be wrong.

[Dirty Duc]

It should be 43.5 psi...

I think it is supposed to be: tank, injector rail, pressure regulator, back into tank... and after I look at the 03 620 parts diagram... I think somebody at Ducati had a little too much chianti with lunch. 

Fuel pressure doesn't matter except in the injector "circuit."  That's where to test it (assuming Ducati is right), after the pressure regulator.  If I am right, swapping the fuel lines at the tank will fix the problem... and if you test fuel pressure after the regulator it will be low.  I'd like to hear either way.

[808Ducati]

thanks.  I actually listed order incorrectly. I have tank, fuel injector rail, regulator (into side, out bottom), tank which I assume is correct.
I tested pressure coming out of rail and into regulator and had about 45 PSI.

[Dirty Duc]

**edit**
It looks like it should go from the fuel rail to the bottom of the regulator. but again, the diagram doesn't show that necessarily.
/edit

***2nd edit***
Is there a vacuum hose going from the top of the pressure regulator to one of the throttle bodies?  Vacuum hose is cheap.  I'd replace it.
//edit

If not:
Dirty injectors.

http://www.mrinjector.us/

[808Ducati]

Injectors are brand new - have tried 2 pair.
The nipple off the top of the regulator where a vaccum hose would normally be attached is open to the atmosphere.  There was never a hose on it in the first place.

[Dirty Duc]

The only major thing left that I can think of is the injectors aren't firing because of a wiring or an ecu issue.

How many miles are on this bike?  I ask because maybe it got some crud in the fuel rail or something, so the injectors aren't seeing full pressure and flow.  will it run with the gas cap open?

From what you have described it certainly sounds like a fuel supply problem.  If it isn't physical, it must be electrical/electronic.

[rule62]

Is there a chance that the coil wires were swapped and that the cylinders are getting spark at the wrong time? Might be worth a quick look-see.

[DarkMonster620]

have you checked for the injector plugs being in the correct injector?

[808Ducati]

About 20,000 miles on the bike.  I could not have reversed the injector wiring as it's not long enough to reach the "wrong" injector.  I'm gonna try and start the bike with an injector pulled (and forced to stay put or else it will go flying out of it's holder) to see what kind of spray I am getting.  I've tested pressure both before and after the rail and it's good.  This test will show me if the injectors are firing.  I did the test before I swapped out the regulator and they were firing but with very little pressure-assuming that was because there was no back pressure.  What does the gas cap have to do with anything???

[LowThudd]

Gas cap can create vacuum lock, if it is not properly venting.

[DarkMonster620]

let me try and recapitulate;

one bad coil > replaced, just that one you state you now have good spark on both
spark plugs > replaced
fuel filter > replaced [installed in correct position?], it happens to everyone every once in a fortnight
injectors > replaced
fuel system: tank > pre-filter > pump > filter > rail > injectors > pres reg > tank â†' checked OK
fuel pres: checked 50psi ~ 3.45bar
hoses under tank: in from pres reg/out from pump >
TPS reading > , http://www.bikeboy.org/ducati2vthrottleb.html  just in case you need it

just thinking as if the bike was here with me . . .below from the >2004 Monster 400/620 Manual


fuel syst m620 mt

[battlecry]

Have a fire extinguisher handy if you pull the injectors to test them.

[808Ducati]

check, check and check.
all correct
have not checked the tps yet