Finally got the engine to start last month. This is what I came up with.
Just so you know, I am not an expert or even a mechanic for Lexus. My experience comes from being pretty good at working on my 65 Mustang, from engine to brakes(much simpler on those cars). I spent quite a few hours on the forums to find any leads to this problem. The one common theme seemed to be the Lack of a Check Engine Light,CEL,when the key was turned to the ON position, the position prior to engaging the starter. This seems to be a very common theme on the 91-96 Lexus SC400 and LS400.
Checked for fuel, there was plenty being pumped into the fuel filter.
Checked the fuses, all good. EFI relay, checked good when pulled then reinstalled. Have the key in the on posit prior to reninstalling the efi relay(so you can listen for the fuel lines being charged) I could hear the fuel charging thru the lines.
After looking at the Club Lexus Forum, noticed a guy had similiar issues: battery drain over time, gradually leading to inability to start , no CEL, and crank but no start.
Decided to buy a used ECU from the junkyard. Make sure it comes from a engine that runs with no caution lights. (Remember to get the one that is suited for the year your car was manufactured,92-94 have same ECU. Location is under the passenger side carpet, close to the firewall. To locate it, pull the carpeting down from underneath the glovebox, carefully removing it from the console, and on the door side(only to the footplate for the door, peel it back and you will see a black plastic cover about 2x 1 ft. Unscrew the 2 nuts at the bottom and remove) Take the one nut off the left side of the ECU(about 10"x10") and pull up and release back clamp) Unplug the wire bundle plugs(you have to remove the cap and then unscrew the bolt on the large one in order to to pull off the plug.)
Plugged new one in and now had a CEL when ign was turned on. Car fired up about 10 seconds after start of cranking and has run great since!
For those of you who may need an Engine ECU, the forum members have them listed in the classified section, Both this Forum and the Club Lexus website(from $25-150).
There are also repair facilities that can do the job in a week or you can order a reman and ship them your core for faster service, $204 @AUTOECU.COM, shipped.
TOYOLEX PARTS, just google ecu rebuild, they pop up there, Autoecu had the best deal.
Best of luck, glad to have my car back in service.
I did toss that solar charger, it's not worth the chance of it causing problems, thanks.