Has anyone ever figured out how many gallons they have left when the low fuel idiot light turns on? It happened to me in Wyoming, noted the mileage, made it to a station and filled up with 26.0 gallons (29 gallon tank). Backing out the miles to where the light came on, I figure I had 4 to 4.5 gallons left. Also by the time I got to the station, the fuel gauge showed just below empty. I realize I may not have topped it off all the way but I tried and the next tank gave me 13.3 MPG (all manually calculated). The tank I ran almost to empty was 12.3 MPG (Heavy head wind and driving 80 to 70 mph). I guess they are built this way to scare you into filling up early. Second long road trip and can't wait for the next.

 

MOST OF MY DRIVING IS LOCAL SO I'M ALWAYS CLOSE TO A STATION TO FILL UP. WHEN MY LIGHT COMES ON IT TAKES RIGHT AT 23 GALLONS TO FILL IT UP. THIS HAS BEEN CONSISTENT TO THIS POINT AND I'M STILL AVERAGING 14-14.5MPG.

 

My 2003 F350 with 38 gal tank consitently has 7 gallons remaining when the light comes on. (yeah....I don't always keep a real close eye on the fuel level)

 

Not that I think for a moment that Ford is this much on the ball with their engineering designes but....

The electric fuel pump in the tank is cooled by the fuel. If you ever run the tank really dry then there is no cooling and the low presure keeps cycling the pump constantly and you run the risk of burning the pump out. If you do not have a fire (and they rarely catch fire) you certainly will not like the time and expense of replacing the pump.

The long, narrow, and tall 29 or 38 gallon tanks can be on a slight decline or incline and the fuel moving to the front or rear can expose the fuel pickup to air. I only assume that the engineers intended for there to ALWAYS be 5-7 gallons in the tank to prevent starvation of the pump.

Least ways this is my take on the EARLY warning light and low guage reading.

Also discussed here and other places id the PITA of "filling up" these tanks.

I used to carry a set of boards that I put the left rear tire up on when I filled up. This turned into a minor disaster one day when I "topped off" the tank with 28.7Gallons and drove about three blocks to my favorite cold beer place. (Texas @ 101F that day).

After a while some people came in and were laughing about the fire department hosing someones truck down outside. We all went to the door to see the action, when to my horror and EXPENSE I saw that it was my truck! The fuel had expanded and was causing a $985 dollor environmental hazard.... emabrrassing lesson.

 

The tank on my dually holds 140 litres. At 84.9 per litre, that's $118 per fill up. I don't let it get below 3/4 of a tank during normal daily driving. $30 at a time doesn't hurt so bad!

Rick

 

Hmm...I just filled up last night and put in 32.8 gallons in my 29 gallon tank. This was from DEAD empty though, needle way WAY past the E-mark. It's...85 degrees outside...I've driven about 3 miles, and no gas is spilling out of my truck.

 

My "X" has a 44 gallon tank......don't even know if I have an "idiot" (low fuel) light. Do I?

 

Yup.

Let me have your truck for awhile. I'll make sure that I return it with the light on.

 

OK, I'm gassin' her up now. Just come by my house and pick it up....but beware of my dog(he was an alligator till we cut his tail off and painted him black). I don't understand it but......he ain't near as friendly now. Anyway, the "X" is in the pen with him. Oh yea, almost forgot, he has the key!!!

 

I don't think I would go back to that station anymore. Sounds like they have the pump set a little low. Very hard to believe almost 4 gallons more is possible.


The time at which the light comes on is in your manual. The exact number excapes me now. Seems I have about 5 gallons left in my 38 gallon tank.

Rob