My 1990 Gas converted Supra wont start !!

[eggybread]

Hi, I have a G reg Suprak MK3 which has a gas conversion. I have just bought it but don't know much about it. There's a switch that changes it from petrol to gas. Must be started on petrol though. Most of the time it starts ok but once every couple of days when i turn the key it just clicks once. I keep trying and after 10 or so attempts the starter motor will kick in no problem but then it sounds like there's no petrol or something as it will not start for a further 15 - 20 attempts. Then it will start to try and splutter before starting and running again ok for probably a day or two. Not sure if it has anything at all to do with the gas conversion as I have a receipt from 1994 where it was taken to toyota for intermittent starting problems and the gas conversion wasnt done til 2001 ! toyota said back in 94 that the car passed all tests and they suspected the alarm. however, if the alarm is switched off on the unit it still does this. Any ideas please ? I have had no response on this yet so if anyone at all has any ideas i'd love to hear. Many thanks, Eggybread.

[supraduper]

your clicking sound, most likely is a bad starter... but could be any numbe of things