gas gauge issues (1 Viewer)

[workingdog]

So, I gots this cool new 20 gallon under seat gas tank from WFO with a combo fuel pump sending unit from a 2012 camaro (because it's low profile) and this fancy doo-dad that translates ohms off the sending unit to ohms for the gauge. And the whole thing works - kind of.

We take a short drive with the tank showing 3/8 to 1/4 tank. Get in the car an hour later and the gauge shows empty and won't move. This has happened twice, the first time I just figured something was wrong with the gauge or the sender and ran out of gas going 1/8th mile to the gas station.

Can anyone shed some light on what's happening? Is it lying when it showing a quarter? If so, why?

 

[Coolerman]

Need more information about how all this is connected. Especially the magic translator.

Also: How did you calibrate it?

 

[workingdog]

It's a Classic Instruments SN34 Fuel Link Interface
You calibrate the sending unit by telling the interface when the sending unit is at empty and when it's a full. It figures out the in between. You calibrate the gauge by using the interface to set the gauge to E, 1/4, 1/2, 3/4, F. And then i knows all that it needs to know.

 

[Solace in Solitude]

So, are you starting with a completely empty tank and telling the interface that the tank is empty... then, filling the tank and telling the interface that the tank is full?

Or, are you moving the sending unit arm (or whatever) to empty and telling the interface that the sender is at empty... then, moving the arm to full and telling the interface that the sender is at full?

Are you using an oem fuel gauge? For what year?

By, "...this fancy doo-dad that translates ohms off the sending unit to ohms for the gauge...", do you mean the doo-dad translates the sender ohms to the oem gauge-expected ohms?

Does the doo-dad account for the potential voltage difference between the sender and the gauge?

Rudi discusses the fuel-gauge/sender ohms and volts and the fact that the sender and gauge HAVE to be used as a matched pair, in this "clusters, gauges and speedo" thread.

 

[workingdog]

I calibrated the sending unit out of the tank (only way I could). setting it next to the tank so I could approximate empty and full.

Autometer fuel gauge (quad gauge).

Yes, the FuelLink takes in ohms from the sending unit and sounds out ohms to the gauge. I have no idea about voltages, I'll read Rudi's thread.

 

[Solace in Solitude]

I don’t know what year gauge you have... my ‘78 gauge steps down to 7v.

I’m not sure you will be able to make and Autometer gauge work with an oem sender (assuming you are using an oem sender).

Autometer makes a sender that works with their gauges.

@bj40green (Rudi) can help, if you don’t find your answer in his thread.

@Coolerman (Mark) can also help.