Elliott, tnx...Yes we tested it like that and it works... but problem still exists...
Maybe pump goes bad when scooter get warm, because when I start to ride it goes great for about 4,5 minutes and then just starts to chocks.
I will try third pump today but maybe pump is not the problem...
I would appreciate if anyone has some other idea...
Yes, the VOLUME MAY BE GOOD AT THE START AND AT LOW PRESSURE, but your problem is occurring after it runs for a few minutes.
THIS is why I said to do the FUEL PUMP PRESSURE TEST. And continue to monitor the fuel pump pressure while you ride it. It is a darn shame that Suzuki did not put a fuel pressure test port on the fuel line. All the cars that I have worked on had one, don't know if the news ones still do tho. You can buy a new fuel line, and cut and modify the old one to be able to measure the fuel pump pressure. After the test, replace the "test" fuel line with the new one.
If the pressure remains good and does not drop after riding for a while when the problem occurs, you can rule out the fuel pump.
However, I believe that you most likely have a restriction somewhere downstream from the fuel pump.
Another thing to check is to be sure the gas tank is getting vented properly. Try this, with the gas tank about 1/4 to 1/2 way full, loosen the gas cap. You can unlock the gas cap, remove it, lock the cap, then put it back on only about 1 turn, to allow venting of the tank. Ride it like this a short distance to see if it makes any difference. This will eliminate or confirm any chances of problems with the tank venting system.