Anyone know how much fuel left in tank when low fuel indicator shows on the dash. 2007 5.4 F150

 

It varies truck to truck

 

It means that you need to put gas in NOW, because running it low can overheat the fuel pump.

 

anybody got any proof to this?

iv heard both that it does hurt it and that it doesnt

sorry for the thread jack


mine comes on when i have 50 miles left

 

Well if the pump is running trying to feed a large truck engine and all it is getting is air and fumes it will run harder with little to show for it. It will hurt it if you run it long enough without anything to pump. I dont have any pictures or temp logs but most fluid pumps do not like to run dry because often they use the fluid to help keep everything moving smoothly. Remove that fluid and it is dry parts rubbing which causes friction which causes heat and wear.

If it is an impeller design pump then it will overheat, the only pump that I've seen that doesn't overheat is the diaphragm style pumps.

You've only got a few gallons left when it comes on so it is not something you should really need to know other than dont count on it to go longer between fills. An easy way to find out is drive until the light blinks on. Then immediately fill. Then find out how much gas your truck is supposed to hold.

 

It's not air and fumes - the fuel pump is kept cool by immersion in the fuel. With a low fuel level, it runs hotter. It's no big deal if it's only occasional, but if you constantly run it down to the light you can reduce the life of the pump.

 

I ran my down to the light last night. Second time I've had it that low usually fill up around half a tank.

I have a 36 gallon tank and this morning when I filled it up I put 28 gallons in.

 

i get that point but its still is somewhat submerged otherwise the truck would stall because its not getten any fuel to pump.

 

54000 Miles on my truck and I just about run it down until I get the light, then fill up, usually 21-23 gal on a 27 gal tank and so far no problems with my pump, so I would say when the light comes on you have about 60-70 miles left to empty, only one question can you run the tank completely dry?

 

Not so, the only fuel pumps I've ever burned up were on race cars with constant low fuel. We never ran more than 3-4 gallons in our FI cars per pass to keep weight down and without the fuel to help cool them we burned up quite a few Bosch and Walbro pumps before their time (6-8 months sometimes) where on street cars running the same setup that were constantly filled up and run down the pumps would last like OEM pumps. At one point I had a Walbro 255 in an all motor car that was 3 years old with no issues seeing 10k a year or so but the same pump in a NA application that was alway run around 1/8 of a tank wouldn't last more than 6-8 months before it started dying.

 

was there like a KB boost a pump on that fuel pump cuz that would kill it to...

 

I've yet to see any real proof that running your tank down to the light is any concern. This thread definitely hasn't provided any evidence...

Just a hunch here... but I'm guessing that it won't run too long without anything to pump. Most vehicles stall immediately when they run out of fuel.

Just another hunch... but I'm pretty sure that fuel pumps don't "get hot". As the pump is submerged in gasoline there is no way that it would be designed such that it gets hot.

not a valid comparison by any means. Race cars are run under totally different conditions.

 

fuel pumps are cooled by the gas sloshing around inside, and they shouldnt be run too low because they can then suck up junk off the bottom of the tank.

my truck is a supercrew short bed 5.4 truck, with a 30 gallon tank. when the gas light comes on (50 miles to empty) my truck will only take about 22-23 gallons worth of fuel depending on what kinda mileage i was getting. i imagine even if you run it down to 0 miles to empty, it would only take 25-26 gallons. i could run my jeep way down below 0 miles to empty, but with this truck i usually start looking for a station when the light comes on.

 

I usually fill up with between 10-20 "miles to E" on the tank. I routinely top of the tank with 26 gallons, and if I get to "0 Miles to E", I have filled up 27 gallons before. That still technically leaves 3 in the tank for cooling. I have run all of my vehicles in this manner for the past 15 years and have never needed to replace a fuel pump.

 

as long as you dont run it dry you wont.