Why my 1985 K100 RS will not start?

My 1985 K100RS had a bad fuel Pump. I changed it, and the fuel filter also. It ran for about 20 mins. But when the battery light came on it stalled. I haven't been able to start it ever since. I took the battery to the dealer. They checked, it was okay. I have checked the sPark plugs, all the wires. Everything seems to be okay. The battery seems to have enough charge to crank the engine, but it won't start. Need help.