Today I noticed my fuel gauge giving a low fuel light. I had just fill up 50 miles earlier. Stop fr fuel anyway and could only put 1 3/4 gallons in so the tank is full.

After fueling the gauge went up off the low fuel mark about what I had put in.

The only other consideration was the batteries were down and charged last night.

Question. What do I look at first?

 

Fuel level float sender thingy (that's the technical term, I'll dumb it down if need be lol).

 

My darn fuel gauge keeps going to E I fill it up & it does the same dang thing Over & Over

 

Same with mine. It wasn't as bad with the 5.4, but the 6.8 it's even worse. I'm looking into a TSB to see if it was a known issue or not. The fuel gauge drops when you mash the gas... I have no idea why

 

If it was just the sending unit why did it react to the 1 3/4 gallons I put in and come off empty?

I have seen fuel additives, government required, melt the resin in carburetor floats. If the float sprung a leak and sunk why the reaction to fuel?

 

Just throwing this out there but if like you said the batteries were down recently that may be the root of your issue. These things are very finicky about having proper voltage to make everything work correctly. Make sure that the batteries are now fully up on charge and give it a drive cycle or two and see if the fuel Gauge sorts itself out with a healthier electrical system driving it.

 

Interesting point.
The batteries are fully charged and Balanced. I took a 3 mile drive and the fuel gauge has come up about 5 needle widths so far.

Not sure I understand why the long time delay but that is what has happened so far.

The last time I got fuel, before this issue, I was running on fumes, if that. The gauge had never been that far down before.

 

Might be wedged down at that point, but if it's moving a little when you top it off that wouldn't make any since.

 

Is it a diesel? Reason I ask, this has happened to me in the past I now
Use a certane booster that lubricates, my problem was solved.