It means you have a leak. If it's black, the fuel filter housing would make a likely suspect.
Your oil is probably leaking. If the car is old, then it's likely to be scrap!
If coolant is leaking from a car it means that your radiator has a hole in it. If this is not fixed the car will over heat.
If it is leaking inside the car, the heater core has failed.If it is leaking inside the car, the heater core has failed.
It means that fuel is leaking into your oil. Possibly the engine has a blown head gasket, you will need to have a compression check done to confirm this.
did you forget to replace the cap on the filler tube ? or you may have a leaking line
if you are leaking gas, one of your fuel lines is leaking. Locate where it is leaking from. DO NOT DRIVE THE CAR IN THIS CONDITION. if it overflowed at the pump out of the fuel door, it may been a faulty pump.
If you mean leaking water in the car then the drain is probably stopped up.
means get it to a repair shop
The overflow tank is either cracked or its overheating and leaking from the cap
If the car has a carburetor this is normal. If the car has fuel injection then are loosing residual fuel pressure. This can be caused by a weak fuel pump that is about to fail. Also can be caused by a leaking fuel line. A defective throttle position sensor is another possibility.
Black smoke from an engine is caused by unburnt fuel.
If the fuel system has a leak it would be leaking fuel. There should not be air in the fuel system unless the fuel tank is empty. If you got a code saying that, Your car might have a loose gas cap, the test pump is bad, fuel sending unit gasket or a problem with the tank vent valve(depending on make/model). Car now a days have to have an EVAP system to check that the fuel system isn't leaking fuel vapor into leaking fumes(HCs) into the atmosphere. I would remove/reinstall the gas cap and clear the fault and rerun the test. If it still is showing a code. Again depending on make/model, there might be a pump self test in the scan tool or you would need a smoke machine to find the leak.