VOILA!* (that's French for "voila.")
* (Mr Emoticon is toasty warm now, not blue any more)
Couldn't just sit here wondering, so I "assumed the position" and crawled down by the heater.
First I got close enough to the sticker on the unit to read that the error code was the number of LONG pulses on the LED after the five SHORT flashes, not the other way around.* So it was actually sending code 1, which was the also very useful "NO START."* Duh.
So I pulled fuel lines and pulsed the pump and nothing came out.* For quite a while, at least.* Thankfully, I spilled no fuel into the bilge; my shirt soaked it up quite nicely, thank you very much (did I mention that I was in "the position" at this time??).
But it finally started dribbling out.* What didn't make any sense was why it stopped pulling fuel, since the filters were full of fuel and the vacuum guage on that side showed no problem.
What's this?* Where the dickens is that fuel line go that supplies the pump???* Followed it back and back and back in the boat... to the mystery fuel tank that I've always assumed wasn't used any more.** It's about a 50 gallon tank, FRP, molded into the inside of the transom.* Since I've never filled it up, it eventually ran dry.**
I was able to get enough fuel out of it to run the heater for a few minutes and confirm that it's otherwise OK.*
I kinda like the idea of having the heater run from a separate tank.* But since I've got the stbd engine heat exchanger pulled apart, I guess I'll have to go get a gas can and pour a couple of gallons of fuel into that tank.
Thanks for the insights on this, guys.* Since it was so obvious that there was no fuel problem, I'd not have tried the fuel pump test.* Any of y'all make it Anacortes way, the beer's on me.
Mystery solved, in any case.