There is probably a bleed valve on the injection pump to get air out of the lines from the tank to the injection pump. It will probably look like a bolt screwed into a larger nut. Hold large nut and open bolt a couple of turns. There will be a hole in the side of the bolt that will let air and fuel out. I use a small amount of air pressure in the tank fill port to force fuel through to the bleed valve but don’t use but a few PSI (.25 bar or less).
Then close the valve and try to start it. If not then move to the pipe connection to the injectors. Here you have to loosen the nuts a couple of turns so the air and fuel can be ejected. Crank the engine starter a bit and then let it rest a minute or so, do not burn the starter up by getting it hot by using it too much. Use the decompression knob if you have one to help the starter spin fast and stay cooler. Eventually the bubbles will disappear at one injector so close that line. Then you can see if it will start or continue to bleed the next injector. (I don’t know how many cylinders 2 or 3 you have?). All injectors need to be bubble free but it can probably start and run on 1 or 2 cylinders. Once it is running, I then open one injector at a time and let it pump air and fuel out to be sure there is no air left. When you crack an injector open with the engine running the RPMs should drop if the line has been bled well.
Good luck, don’t get discouraged and bleed it longer and more times than you think you should have to.
