Ah, yes. Now it is all coming together!
One issue that does not seem to come up too often is the “overflow pumping” flaw in our US implementation of the subtank system. Stated simply, the vehicle operator has to have sense enough not to engage the subtank transfer pump and attempt to transfer fuel into the primary tank when it is already full.
There is no ECU logic (primary tank is full signal) to prevent the subtank pump from activating, and pumping forever as the fuel goes round in an endless loop. This secondary, 3/4 full switch in the primary tank undoubtedly sends that signal to the fuel transfer ECU to prevent this condition.
Now, all we have to do is wait for Mr Mariachi to identify this switch, for our parts Guru to source the part, and for George to redesign his “ECU” to accommodate the signal.
In the mean time, a second fuel gauge or a switch to select which of the two fuel level senders the primary fuel gauge is looking at, is a much simpler way to remind the operator that both tanks are full and to not do anything foolish. The single gauge with a switch to select the sender is the way I do it... I can never trust the vehicle operator to remember which tank (or both?) has the fuel in it.
Cheers, R -
One issue that does not seem to come up too often is the “overflow pumping” flaw in our US implementation of the subtank system. Stated simply, the vehicle operator has to have sense enough not to engage the subtank transfer pump and attempt to transfer fuel into the primary tank when it is already full.
There is no ECU logic (primary tank is full signal) to prevent the subtank pump from activating, and pumping forever as the fuel goes round in an endless loop. This secondary, 3/4 full switch in the primary tank undoubtedly sends that signal to the fuel transfer ECU to prevent this condition.
Now, all we have to do is wait for Mr Mariachi to identify this switch, for our parts Guru to source the part, and for George to redesign his “ECU” to accommodate the signal.
In the mean time, a second fuel gauge or a switch to select which of the two fuel level senders the primary fuel gauge is looking at, is a much simpler way to remind the operator that both tanks are full and to not do anything foolish. The single gauge with a switch to select the sender is the way I do it... I can never trust the vehicle operator to remember which tank (or both?) has the fuel in it.
Cheers, R -
