'91 300CE (M104) won't start - disconnect EHA & it starts! Why??

[rgnprof]

I have been tracking down fuel related issues on my 300CE for a while. This afternoon, I drove it about 10 minutes, shut it off and tried to start it again in an hour so - car just cranked and cranked. Didn't sound like it was getting fuel...

Let it sit for 4 hours or so and tried to start it again - same thing, although it tried to catch this time. Unplugged the EHA valve and it started right up and drove home just fine.

What's going on here? Any suggestions or ideas?

ryan