How do you drop the fuel tank off of the car

I would say tank. If the filler neck was leaking, it would be doing it the entire time you fill up. Get it fixed ASAP- that can be a serious fire hazard.

Trouble Code: P0442

EVAP Control System Small Leak Detected

Possible Causes:


Canister Purge valve is damaged, leaking or it has failed.Charcoal canister is loaded with fuel or moisture.Fuel filler cap loose, cross-threaded, incorrect part or damaged.Fuel tank is cracked (leaking), or a leak exists in the 'O' ring.Fuel tank pressure sensor is damaged or has failed.Fuel vapor line(s), fuel pipes or hoses damaged or leaking.PCM has failed.

If the leak is coming from the top you could have a damaged gasket for the fuel gauge sending unit. If it looks like a seam or a puncture, you need a new tank.

May be leaking from top of tank where fuel pump mounts. If vehicle has been forced overful several times the gasket will get damaged and leak. Sooner or later tank will need to be dropped and change pump and gasket. I recommend AC Delco pump ( original )

If the smell is coming from the back of the vehicle then it could be leaking from the return line or the filler hose. I would check the fuel filler hose first since you can probably get at it wihtout dropping the tank. You might be able to get to the return line as well which is a small hose that goes to the tank from the fuel pressure regulator to return unused fuel. If the smell is coming from the front of the vehicle I would inspect all of the fuel lines and the inline fuel filter if you have one installed and verify that none of the hose is damaged and all clamps are tight. Check your injector rail and make sure it is not leaking where it provided fuel to the injectos and check your injectors seat to see if there is any evidence of fuel leakage.

If you can't find any leaks in those locations then you are gonna have to drop the tank and check the pump.

Trouble Code: P1456


EVAP System Very Small Leak (0.020") Detected

Possible Causes:


EVAP control system pressure sensor is damaged or has failed

EVAP purge solenoid is damaged or has failed

EVAP canister vent control valve is damaged or has failed

Fuel tank cap not tightened properly or the wrong part number

Fuel tank temperature sensor is damaged or has failed

Fuel tank vacuum relief valve is damaged or has failed

Very small leak in the EVAP canister or in the fuel tank area

ORVR system is damaged or has a small leak in a component

Refueling control valve is damaged or has failed

Sorry. Got to drop the tank. Just break the gas tank bolts and replace them with new ones. If the straps are badly rusted, replace them, too. Look for tank leaks on the top of the tank. Replace the sock on the fuel pump.

The evaporative leak detection diagnostic strategy is based on applying a vacuum to the EVAP system and monitoring the vacuum decay rate. The VCM monitors the vacuum level via the fuel tank pressure sensor input. At an appropriate time, the EVAP purge solenoid and the EVAP vent solenoid turn ON, allowing the engine vacuum to draw a small vacuum on the entire evaporative emission system. If a sufficient vacuum level cannot be achieved, a large leak or an EVAP system malfunction is indicated. The following conditions can cause this problem:
A disconnected or malfunctioning fuel tank pressure sensor.
A missing, malfunctioning, improperly installed, or loose fuel cap.
A disconnected, damaged, pinched, or blocked EVAP purge line.
A disconnected or damaged EVAP vent hose.
A disconnected, damaged, pinched, or blocked fuel tank vapor line.
A disconnected or malfunctioning EVAP purge solenoid.
A disconnected or malfunctioning EVAP vent solenoid.
An open ignition feed circuit to the EVAP vent or purge solenoid.
A damaged EVAP canister.
A leaking fuel sender assembly O-ring.
A leaking fuel tank or fuel filler neck.
Any of the above conditions can set a DTC P0440.

Your may have to drop the tank and check the vent valve, see if it's broke off at the vacuum line fitting since you mentioned that gas las leaking from the tank. 
When checking the vent/purge solenoid, depends on whether you have a 2dr or a 4dr. I can't remember the exact location of the 2dr vent/purge solenoid, but on a 4dr, just drop the spare tire if you have it underneath and it'll be in the middle of the cross member directly behind the rear axle. It'll have one large vacuum line and an electrical connector. 
You can also see the gas filler tube to the rear of the gas tank, check for any damages where the gas may be coming out of.
Good luck and hope this saves you some money, I believe most dealer will charge close to $400.00 to drop the gas tank and do this job.

sounds like you are going to have to drop the tank out to inspect and fix. with luck it will be leaking from the fuel pump seal or the return line.
Bad luck would be if the tank is rusted out and needs to be replaced.
Syphon as much gas out of the tank as you can before you drop it , gas is heavy.

Well because of the age I think you need a new fuel tank. It could be a rotted fuel line, sending unit, or hose . You will still need to drop the tank to find out what you need. NOTE, use up most of the fuel before dropping it. you dont want it to fall freely or damage will come to electrical components.