Hyundai Sonata LF: Engine Control System / Injector Troubleshooting
The three waveforms below are taken from the #1 and #4
injectors. The top waveform is from the high side (feed side) of the #1
and #4 injectors, while the middle waveform is from the low side (ground
side) of the #1 injector and the bottom waveform is from the low side
of the #4 injector.
The middle waveform is the same as the top waveform because
there is no ground for the circuit. With no current flowing in the
circuit, the #1 injector is not energized and fuel does not flow.
The bottom waveform shows that ground is supplied and there
is a voltage drop across the #4 injector. With current flowing in the
circuit, the #4 injector is energized and fuel flows.

Other information:
Removal
1.
Turn ignition OFF and disconnect the negative (-) battery cable.
2.
Remove the floor console assembly.
(Refer to Body - “Floor console assembly")
3.
Remove the EPB switch after loosening the screws.
4.
Install in the reverse order of removal...
Inspection
[Fuel sender]
1.
Turn the ignition switch OFF, and then remove battery (-) cable.
2.
Remove the fuel pump assembly.
3.
Using an ohmmeter, measure the resistance between terminals 1 and 6 of sender connector (A) at each float level...