Problem keeping my truck running. Keeps dying.

I have a 85 or 86 Nissan small Pickup truck. Not sure what year or model. Truck shows manufacturer date as 5/85.

It has a 4 cylinder but with 8 plugs. Engine has Nissan Z on top of it. It is a Manual Transmission. Not sure what model though.

My friend gave me this truck a few days ago and he had explained to me that it ran at one point but one day he was coming home 1 day and started running out of gas and he explained to me that him and another person for some reason thought they would pee in the tank to help get them home, LoL Don't know why they would do that but anyways he had started to have problems with keeping it running after that even after the tank has went empty a couple times and he has cleaned the fuel filter and then we have tried carbeurator cleaner that you spray into carbeurator and havent been able to keep the thing running.

If you keep pumping the gas, it stays running but pops and sputters real bad and as soon as you stop pumping the gas, it dies.

It won't hardly drive on the road either. It will just pop and sputter when pumping the gas.

What do I need to do to get this problem fixed and running good again? :(