95 suburban wont start...need advice?

Just bought 95 suburban it had been sitting for at least a month....test drove it ran perfect...on my way home itover heats turns off and throws all the coolant out of the coolant tank...so I get more coolant in it...made it about 2 blocks and it just turns off and I havent been able to get it started...it turns over but doesnt start..i can hear the fuel pump turn on.....so im just wondering what it could be?