I noticed today a strong smell of petrol while driving. I had the switch running on the right side and stopped for fuel. The fuel from the station didn’t want to come out of the hose so I thought maybe that side was already full and tried filling up the lefthand fuel tank instead. I turned the car around and pressed on the switch to activate the left side (just to see how full it was). It marked full so I got out and I saw fuel tank overflowing.
I read on this forum that it’s common for the right side to overflow. I had that problem fixed by changing the changeover valve and the right side return valve.
Now about 2 months later, my left side started overflowing. Could it be my left side return valve that needs to be replaced?
The left return valve is normally open so either it has no power or it is stuck.
I would first check for power (the right hand tank needs to be selected and the ignition on, or even the engine running, not sure). If not it is possible that it is shot given that you changed the others.
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Fuel should return to the tank it is taken from, Eddie - if it is taken from one tank and returned, partially or fully, to the other tank, it will overflow.
This ‘crossfeed’ is usually caused by the return valve on the overflowing tank failing open, but may also be caused by a changeover valve failing to respond. Either may fail mechanically or, as David says, electrically.
The first step is to verify return; open filler lids, run the pump, selecting alternative tanks - and listen to fuel returning. Fuel should only(!) return to the selected tank - if it returns to the ‘wrong’ tank; change that return valve. If the fuel returns correctly, but a tank still overflows; the problem is with the changeover valve…
To avoid overflow while musing; set the changeover switch to the opposite position of that causing the overflow. Fuel will then be drawn from the overflowing tank, allowing normal driving until the fault is remedied…
As an aside; any valve may fail, there is no preference - but selecting ‘left’ leaves all valves unpowered, leaving them in the default positions. With ‘right’ selected; all valves are powered, so electric faults will usually only affect the ‘right’ settings - and changing valves will have no effect if an electric fault is outside the valves…