Fuel filter is probably a good place to start, but no guarantees. The correct test is to do a fuel pressure test:
2001 > G 2.4 DOHC > Fuel System
FUEL PRESSURE TEST (2.4 DOHC)
1.Reduce the internal pressure of the fuel pipes and hoses by the following procedures.[/align]a.Open the trunk door and disconnect the fuel pump harness connector in the trunk room.[/align]b.Start the engine and after it stalls, turn the ignition switch to the OFF position.[/align]c.Disconnect the battery negative (-) terminal.[/align]d.Connect the fuel pump harness connector.[/align]2.Remove the bolt connecting the fuel line to the fuel delivery pipe.[/align]Cover the hose connection with a shop towel to prevent splashing of fuel caused by fuel residual pressure in the fuel line.[/align]
3.Using the fuel pressure gauge adapter, install the fuel-pressure gauge to the fuel pressure gauge adapter. Tighten the bolt to the specified torque.[/align]4.Connect the battery's negative (-) terminal.[/align]
5.Apply battery voltage to the terminal for the pump drive and activate the fuel pump: then, with fuel pressure applied, check that there is no fuel leakage from the pressure gauge or connection part.[/align]6.Start and run the engine at curb idle speed.[/align]7.Disconnect the vacuum hose from the pressure regulator, and plug the hose end. Measure the fuel pressure at idle.[/align]
8.Measure the fuel pressure when the vacuum hose is connected to the pressure regulator.[/align]9.If the results of the measurements made in steps (7) and (8) are not within the standard value, use the table below to determine the probable cause, and make the necessary repairs.[/align]Condition[/align]Probable cause[/align]Remedy[/align]Fuel pressure is too low[/align]a.Clogged fuel filter[/align]b.Fuel leakage to the return side, caused by poor seating of the fuel-pressure regulator[/align]a.Replace fuel filter[/align]b.Replace fuel pressure regulator[/align]
a.Low discharge pressure of the fuel pump[/align]a.Check the in-tank fuel hose for lage or replace the fuel pump[/align]Fuel pressure is too high[/align]a.Sticking fuel-pressure regulator[/align]b.Clogged or bent fuel return hose or pipe[/align]a.Replace fuel pressure regulator[/align]b.Repair or replace hose or pipe[/align]There is no difference in fuel pressure when the vacuum hose is connected and when it is not.[/align]a.Clogging, or damaged vacuum hose or the nipple[/align]b.Sticking or poor seating of the fuel pressure regulator[/align]a.Repair or replace the vacuum hose or the nipple[/align]b.Repair or replace hose or pipe[/align]10.Stop the engine and check for a change in the fuel pressure gauge reading, which should hold for approximately 5 minutes, If the gauge indication drops, observe the rate of drop. Determine and remove the causes according to the following table.[/align]Condition[/align]Probable cause[/align]Remedy[/align]Fuel pressure drops slowly after engine is stopped[/align]a.Injector leakage[/align]a.Replace injector[/align]Fuel pressure drops immediately after engine is stopped[/align]a.The check valve within the fuel pump is open[/align]a.Replace fuel pump[/align]11.Reduce the pressure in the fuel line.[/align]12.Disconnect the hose and the gauge.[/align]Cover the hose connection with a shop towel to prevent splashing of fuel caused by fuel residual pressure in the fuel line.[/align]13.Replace the O-ring of the end of the hose.[/align]14.Connect the fuel hose to the delivery pipe and tighten with the specified.[/align]15.Check for fuel leakage.[/align] [/align] findme('); findme('); findme(');
Looks like the fuel filter is underneath the car near the fuel tank.
2001 > G 2.4 DOHC > Fuel System
FUEL FILTER REPLACEMENT (2.4 DOHC)1.Reduce the internal pressure of the fuel lines and hoses and perform the following operations.[/align]a.Disconnect the fuel pump harness connector in the trunk room.[/align]b.Start the engine and, after it stops, turn the ignition switch to OFF.[/align]c.Disconnect the battery negative (-) terminal.[/align]d.Connect the fuel pump harness connector.[/align]2.Remove the two fitting nuts while holding the fuel filter nuts securely.[/align]
3.Remove the fuel filter mounting bolts, and then remove the fuel filter from the fuel filter clamp.[/align] [/align] findme('); findme('); findme(');
Another possiblility is the exhaust camshaft coming out of time. Have you replaced the timing belt? Here is the TSB:
2001 SONATA/SANTA FE 2.4L ENGINE RUNS ROUGH, IDLES ROUGH, DTC P0335[/align]DESCRIPTION:[/align]Some 2001 MY 2.4L Sonata and Santa Fe vehicles, customers may complain of one or more of the following conditions:[/align]Rough running.[/ul]Rough idle.[/ul]Lack of power at low rpm.[/ul]Check engine light on (DTC P0335 crankshaft position sensor malfunction).[/ul]This condition may be caused by the exhaust camshaft coming out of time.[/align]A new timing belt cover P/N 21360-38214-D that incorporates a timing belt guide has been installed on vehicles produced since January 30, 2001.[/align]Vehicles that experience the condition described above should be updated with the new timing belt cover[/align]
[/align]INSPECTION:[/align]Inspect the production date of the vehicle. Vehicles produced on or after January 30, 2001 are not affected by this TSB.[/ul]Remove the upper timing belt cover.[/ul]Rotate the crankshaft until the timing mark of the intake cam sprocket is aligned with the timing mark on the rocker cover.[/ul]Inspect the alignment of the timing mark on the exhaust cam sprocket with the timing mark on the rocker cover:If the exhaust timing mark is properly timed, skip to step 13.[/align][/ul]If the exhaust timing mark is NOT TIMED properly, continue to the service procedure section.[/align][/ul][/ul]SERVICE PROCEDURE:[/align]Remove the right front wheel and engine splash shields.[/ul]Lower the vehicle and support the engine with a floor jack.[/ul]Remove the right side engine mount, water pump pulley, accessory drive belts, and lower timing belt cover.[/ul]Set the engine to top dead center (TDC) and set the intake and exhaust cam sprockets on their timing marks (as close as possible).[/ul]Remove the auto tensioner and timing belt.Inspect the timing belt. If its worn, cracked or frayed, replace it.[/align][/ul]Inspect the tensioner. If its leaking fluid, replace it.[/align][/ul][/ul]Slowly compress the tensioner in a vise (apply pressure until resistance is felt, allow tensioner to compress, then apply more pressure) until the locking pin can be re-installed. A locking pin is supplied with a new tensioner. If an extra locking pin is not available, a 3/64" steel pin can be substituted.[/ul]Install cam sprocket holder (SPX/Kent-Moore P/N 09231-38000) to hold the cam sprockets in alignment during timing belt installation. Install the tool 1/4" deep after the sprocket timing marks are in alignment.NOTE[/align]Insert the tool only 1/4" to make it easier to remove after the timing belt is installed.
[/align][/align][/ul]Verify the following timing marks are aligned (refer to photos below):Camshaft sprockets (intake 1, 2; exhaust 3, 4)[/align][/ul]Balance shaft (5, 6) and oil pump sprocket/balance shaft (7, 8)[/align][/ul]Crankshaft (9, 10)[/align][/ul]
[/align][/ul]Wrap the timing belt in a clockwise direction starting from the intake cam sprocket. Keep the belt tight when installing over the exhaust cam sprocket, oil pump sprocket/ balancer, and crankshaft.[/ul]Apply hand pressure to the tensioner pulley to take up any slack, and remove the lock pin from the tensioner. Remove cam sprocket holder.[/ul]Rotate the crankshaft clockwise (by hand) 2 complete revolutions and set to TDC. If the TDC mark was passed, then rotate the crankshaft another two complete revolutions. The crankshaft must only be turned clockwise for proper tension and orientation of the timing marks.
[/align][/ul]Inspect the timing marks of the cam sprockets for proper timing.NOTE[/align]Due to the difference in ratio between the crank sprocket and the oil pump sprocket, the oil pump sprocket will appear out of time after turning the crankshaft 2 revolutions (provided the sprocket was set properly in steps 8 and 9). The oil pump sprocket will come into alignment on the 6th revolution (1 : 1.5 ratio; crank to oil pump).
[/align][/align][/ul]If the timing marks are properly timed, rotate the crankshaft an additional 90 degrees to take the marks off of TDC.[/ul]Reassemble the engine (if applicable) and install new timing belt cover P/N 21360-38214-D.[/ul]WARRANTY INFORMATION:[/align]OP CODE[/align]OPERATION[/align]OP. TIME[/align]OP. QTY[/align]NATURE CODE[/align]CAUSE CODE[/align]21361R00
Timing Belt Cover Replacement
Timing Belt Replacement