I had the same problem, I cleaned the connector of the start injector time switch and I seen that connectors "STA" and "STJ" stays releases and did not engage correctly, I have also changed the Star injector time switch and now it starts very well.
Look at here:
http://www.cygnusx1.net/supra/library/TSRM_MKII/fi/FI_071.html
(Excuse me for my English is not really good)
Look at here:
http://www.cygnusx1.net/supra/library/TSRM_MKII/fi/FI_071.html
(Excuse me for my English is not really good)