From the information I gathered it is very unlikely it is the siphon pump, as it is just a number of passive pipes. What is more likely is that the fuel pump is not generating enough volume of fuel to come back through the return line which in turn makes the siphon pump move the fuel from the left side using venturi effect. This can be caused also by the clogged fuel filter of course. Even if the pump is ok, I would rather replace it since the car has around 120k miles and I am not familiar with the maintenance history.

I completely agree with the rest of the info.

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2003 / 3.0i / Auto