What can cause an ECU failure?

Possibly Not! If the pintle valve within the injector is stuck or gummed up you probably won't hear any pulsing.

Even if you did hear the pulsing, you don't know if the internal filter basket or spray tip is blocked or gummed up!

You need to get to the Injectors. Unplug one at a time, make sure the ECM flags a fault code for each one, this will at least confirm wiring continuity and most likely a serviceable ECM.
Again, do as Squirrelman suggests, try starting then check a plug or two for being dry = no fuel being injected.

 

Oh darn!

 

I've removed the base of the air box. Is there an 'easy' way to remove the fuel injectors without removing the throttle body? The method in the manual appears quite intensive.

Yep, having fun!

 

The injectors have been removed and boxed up to send for cleaning. I wonder who the engineer was who decided that the fuel rail had to be attached in such a way that the throttle bodies had to be removed to access the four mounting bolts. Ahh well.

 

Understand your frustration. Will be interesting to see the report on the state of the Injectors. With the Throttle Bodies removed this gives you a good opportunity to inspect all vaccum hoses as well as thermostat housing hoses etc.

 

The injectors were returned today. Before cleaning one didn't spray at all, while one was 'fair' and two were 'good'. After cleaning they were all rated 'good'. Note that there was no observable spray from any of them before they were removed from the bike. It will be interesting to see if they now spray. Fingers crossed! Fast turn around--7 days which included shipping back and forth. Race City Injector in Mooresville, NC.

 

Very interesting thread, I'm looking forward to the conclusion. Good luck

 

My, how time flies! The update: I agonized for at least a month on how to install the injectors--whether to place them first into the throttle body or the fuel rail assembly. There is the matter of alignment of the 4 injectors since they are angled towards each other. I ended up placing them into the throttle body, attaching the electrical connectors and then placing the fuel rail assembly over them. No drama, thankfully. And happier still the bike started after perhaps two tries--and runs great! Such fun.

 

Agree. Glad the bike is running well and all sorted.

The Bottom Line! - There was NO ECM issues (lots of diversions from the problem) and the root cause was gummed up Fuel Injectors from years of storage inactivity.