I have a 2000 Honda Accord that uses petrol & gpl gas (lpg), all the electrical system & engine shuts off on the motion. This happens every time I refill the gpl. Can someone give an answer to it?

If the CEL comes on for 2 seconds and then goes out, when the ignition switch is turned to ON (Position II), then I would replace the Ignition Control Module (ICM) and coil:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-4.html#post265896

If it doesn't do it, when you're only using petrol, then it's some other problem.