Fuel sending unit help

[Jamoaus]

How does engine run when switched to aux tank?
If it runs OK then mechanical fuel is working, and there is no need for electric pump at main tank.
Remove electric pump and connect fuel line to main tank.
If it won't run when on aux tank, fix mechanical pump.

Engine runs fine on Aux, but I did notice that the fuel gauge is now just showing empty. On the main with the pump, it shoots up to about 3/4 full which is about right. Switching to aux just shows empty even though I know the aux tank is full. I swear both were showing full when I did the install but as soon as I started it up, the aux went to empty. Any idea what could be happening? Maybe a faulty sender now at the aux tank?

 

[billh1289]

Engine runs fine on Aux, but I did notice that the fuel gauge is now just showing empty. On the main with the pump, it shoots up to about 3/4 full which is about right. Switching to aux just shows empty even though I know the aux tank is full. I swear both were showing full when I did the install but as soon as I started it up, the aux went to empty. Any idea what could be happening? Maybe a faulty sender now at the aux tank?

Did the gauge ever work with the aux tank? Try jumping the contacts in the connector to see if the gauge will peg.

 

[Jamoaus]

Did the gauge ever work with the aux tank? Try jumping the contacts in the connector to see if the gauge will peg.

No the aux gauge never worked when I bought it from the PO. But when I installed the electric valve, I thought I had both tanks reading on the gauge without starting and when I started it, the aux gauge dropped to empty. I'll try jumping the contacts and also see if I'm getting any ohms from the aux sending unit

 

[bmc69]

Usually there is a an orange sending unit wire from the rear tank and a yellow sending unit wire from the Aux tank. They go to the switch to the left of the steering wheel on the dash and you select which fuel tank level you want to read on the gauge.

I've only run across "all orange" sender wires on my EBs... Just throwing that out there. If only one tank, the functional sender wire gets plugged directly in to the orange to the gauge. Two tanks, just like you described with the switch.