Hello all of you good guys who advised me on this.

Here's what's happened to date:

I got the giant socket at Amazon for about $11 and bought a set of metric box wrenches to bring it up to $25 for the free shipping (we get scre@#ed something awful on shipping to Hawaii). I bought a 1/2" to 3/4" adapter at Sears ($7) so I could use the giant socket, and borrowed my friend's wobble 1/2" handle.

I struggled mightily to get that 46 mm in-tank screen undone. Finally a combination of cutting away the annoying rubber gasket from around the thing so I could get the socket on it, chiseling at it with a metal chisel and small hammer (note - don't do too much of this, it's made of aluminum and shards start to come off), and tying one end of a rope to the wrench handle and making a loop for my foot at the other end so I could use my leg to apply force to the wrench while wedging the socket onto the very shallow nut with a piece of wood between the socket and the axle, did the job.

I was immediately showered with diesel which splashed over the axle and on to me, and not into the carefully placed basin I had there. Note: your fuel gauge is a poor guide to how much fuel you have left in your tank! Suggest siphoning AS MUCH AS POSSIBLE out before you do this. The fuel only trickled out from the fuel delivery hose when I disconnected it from the in-tank screen - which I guess means the screen was badly clogged. I quickly stuck the screen back in to stem the flow and let the fuel slowly leak out into the basin. I now have about 6 gallons of dirty fuel in cans in the garage.

Inspected the in-tank screen. It was about 1/2 coated with black slime. Cleaned it all off nicely and put it back in, torquing only to snug as I imagine I'll be doing this again soon. Put new filters in under the hood. The old prefilter was completely black. Probably could have got away with just changing that! Kind of makes me wonder why I didn't inspect it more carefully before launching into this... as Biodiesel300TD actually suggested. Oh well, the easy path has never been mine.

Got a can of Lubro Moly diesel purge, set it all up with the bottle under the hood. Put a gallon of clean fuel in the tank for after the purge was done. Then struggled for a long time to get the car to start on the Lubro Moly. I decided that the problem was the empty filters so I filled up the screw-on one with Lubro Moly and the pre-filter with a little diesel (used an eyedropper). Finally got it started and the purge lasted about 15 minutes before I was almost out. Put the remaining lubro moly on the ground so I could kick it over later, reconnected the hoses and drove down the street for a while. Seemed quieter and running smooth.

The next day I went and put $40 worth of fuel in (about a gallon at Hawaii prices) and bought a bottle of Soltron which I think is the same as Startron, and added an ounce or so of that. Drove around long enough to get the car warm - maybe 8 miles, and sure enough it started in with the sputtering and stalling again. Hopped out and inspected the prefilter. Full of gunk, but now a different color gunk, kind of orange/brown. I took it out, blew through it, and cleaned the gunk out as much as possible, put it back in and the car started right up.

I guess I still have a lot of crap in the tank/lines and may have to either clean the tank - God help me - or be prepared to get out of the car with my screwdriver and blow the crap out of the prefilter every 10 miles. This will impair my otherwise elegant lifestyle , but I really don't want to take out the tank. I'm hoping that after a few hundred times the gunk will be used up. I've ordered an inline filter for which you can buy replacement filter elements (Spectre 2369) in preparation of the long haul.

What would be good is if I could recirculate the fuel through a big filter outside the car for a few hours to try and get that junk out of there. Million dollar idea for someone out there - come up with a kit to do this. Or does it exist already?

Thanks to all of you for your helpful advice. I'll probably post some more later.

Phil, Honolulu

I remembered that Biodiesel300TD suggested that it might be a vacuum in the tank problem, so when the car was warmed up and starting to experience sputtering again I took the filler cap off, but rather than vacuum there seemed to be considerable positive pressure that rushed out. I left the cap slightly ajar. Could this pressure build up be part of the problem?

YES.

Here is an example of what happens with vacuum.

What happens when a tank vent gets clogged.
What happens when a tank vent gets clogged.