How does the C350 cdi fuel system work ?

[steve-V8s]

Underneath the the rear seat I find two Bosch items. On the right A 204 470 2294 which has two thick wires presumably power supply and two thin presumably level sensor. There are no externally visible pipes on this side. On the left is A 204 470 035 which has two thi wires and two pipes. The wires appear too thin to be power.

How does all this work ? Plainly fuel needs to balance somehow between the tank either side of the transmission tunnel but with no pipes coming off the side with the thicker wires I am puzzled as to what happens.

The tank is currently fairly full so can't remove the pumps to look inside

I am poking about here because engine light is on and I have error code which points to electric fuel pump however car seems to run OK. After clearing the code it returns immediately.

[TheEnd]

There's a siphon jet pump.

The thin wires are level sensors for each side, the thick ones are the tank pump.
The return fuel is sprayed over the end of a pipe which creates a siphon effect to balance each side.

[steve-V8s]

TheEnd said:

There's a siphon jet pump.

The thin wires are level sensors for each side, the thick ones are the tank pump.
The return fuel is sprayed over the end of a pipe which creates a siphon effect to balance each side.

Ok, that explains the balancing but the pipes appear from the side with only thin wires so the pump is on the other side, how does it feed the fuel, is there an internal pipe ?

[CarsOrBikes]

Isn't the n/s pump the engine supply, and the o/s pump the equalising pump? I recall this being so. Fuel return to o/s? I recall the o/s collecting debris mostly after incorrect fuelling when the pump breaks up. I wouldn't look at pumps with out renewing a filter first which you may have done