I'm trying to figure out what happened here. Appreciate any help.

I was on a road trip yesterday when the FEH low fuel warning came on around 400 miles on the Scangauge, as expected. Always in the past the tank would take 12-13 gallons to completely fill, and that would agree with the SG. This time the gas pump stopped at 15.2 gallons to my surprise.

The only extenuating circumstance was I was driving in very heavy winds, so I would expect my mileage to be greatly reduced. But wouldn't the Scangauge accurately track my real mileage?

Can an FEH tank actually take 15.2 gallons? I'm thinking there's a problem with the gas pump (Shell).

 

I have gotten just over 14 gallons. There has only been one poster that stated it was possible to do what you did if the vehicle was on a lateral slope.

 

I have driven mine to completely empty only once. The "Stop Safely Now" warning appeared and I was able to drive, on battery with the ICE off, down to 28% SOC into the gas station, which was less than a mile away. Filled it 14.5 gallons. My understanding is that there is an automatic shut-off with 0.5 gallons left in the tank to provide protection, but after that experience I never let it get below 0 Miles to Empty.

 

Just to followup on this, the Dept of Weights and Measures tested the pump in question and found it was accurate. So my FEH did somehow take 15.2 gallons and wasn't parked at an obvious angle when fueling. Last two tank mileages averaged out to my usual mpg so that extra gas was there and got consumed.

 

The physical volume of the tank is approx. 17.5 gallons. I've pumped in 17.x myself so yours is not unusual.

It is a 15 gallon "nominal" fill. But the filler neck is not at the highest point. On a normal day there is always 2.5 gallons of "vapor space" in the tank. This is by design and allows for expansion and contraction.

When I'm going way out in the middle of nowhere and want to take extra gas along I shake the car vigorously to get some air to "burp" out. With repeated attempts I can pump an additional 2-2.5 gallons after the automatic pump stops.

Hope that helps.

 

Thanks John, good to know. I'll try that burping technique at the next fill up.