Where is the inline fuel filter located on a 2001 plymouth neon?

Fix ? You mean replace ! An not hard to replace , may need special tool's to do it . Look on youtube , may be a video showing how to do it. How to Replace Fuel Filter on 1997 Neon Plymouth

Doesn't have a kill switch , check ASD relay in the under hood fuse/relay box . Or fuel pump relay . Does your vehicle have spark at spark plugs ? Try spraying some carburetor cleaner into the throttle plate an see if it try's to start. The ASD relay powers the injectors an ignition coils .

Filters are either close to the tank on the passenger side or right behind the drivers door, mounted to the inside of the frame.

You change your spark plugs, plug wires, air filter, and usually a fuel filter, but since you have a chrysler product this isn't an option. I would dump a can of sea foam in the fuel tank just for good measure.

The 98 and 99 neons don't have a fuel filter, they have a fuel screen that is right in line with the fuel pump. If your car is not starting and blowing fuses for the fuel pump, you will need a new fuel pump.

FUEL FILTER , CHECK FOR SPARK ON WIRES IF NO SPARK COIL PAK , COULD BE TIMING BELT OR CRANK SENSOR

WELL THE NEON HAS A COMBINATION FUEL FILTER PRESSURE REGULATOR ASSEMBLY LOCATED ON TOP OF THE FUEL PUMP MODULE IN THE FUEL TANK.

i think it may be a inline filter under body of car

Yes you can. I believe you can!
The Fuek Filter is located above the Fuel Tank. You don' have to remove the Fuel Tank but you do have to slightly lower one side of the Fuel Tank to gain access to the Fuel Filter and hose connection to the Fuel Tank from the Fuel Filter. Slightly lowering the tank requires not removing completely the bolts holding the metal straps.
Take you time. Do this a away from a heating source. Have a Fire extinguisher in the Ready Position (Ring Lock pulled and readily (immediately) available). Do not smoke while changing. Have ventilation and kitty litter to absorb any spilled gasoline. AND Disconnect the negative side of the Battery before starting.

Removal & Installation
CAUTION Do not allow fuel spray or fuel vapors to come in contact with a spark or open flame. Keep a dry chemical fire extinguisher nearby. Never store fuel in an open container due to risk of fire or explosion.

1. Before servicing the vehicle, refer to the Precautions section.
   
2. Properly relieve the fuel system pressure.
   
3. Disconnect the negative battery cable.
   
4. Disconnect the quick-connect fuel supply line from the filter/regulator nipple.
   
5. Depress the locking spring tab, located on the side of the fuel filter/regulator, then rotate 90 degrees and pull out. Be sure the upper and lower O-rings are still on the filter assembly.
   

Depress the spring tab, then rotate and pull the fuel filter assembly out


To install:

1. Lightly coat the filter O-rings with clean engine oil. Insert the filter into the opening in the fuel pump module, then align the 2 hold-down tabs with the flange.
   
2. While applying downward pressure, rotate the filter clockwise until the spring tab catches in the locating slot.
   
3. Attach the fuel line to the filter/regulator assembly.
   
4. Connect the negative battery cable.