Kramer test drives car on Seinfeld - YouTube

That is a great episode. I love when Putty adds all the things he forgot to charge Jerry for and one of them is keys.
Jerry: "Keys?!"
Putty: "Yeah, how are you going to start it?"

 

That is a great episode. In our family, if you drive past fuel gauge warning, we call it "pulling a Kramer".

I've gone about 8 miles past "0 miles to Empty". I generally prefer to get gas as soon as "50 miles" warning.

 

At least 30 miles and there was still over a gallon of fuel left in the tank.

 

You really are pushing your luck and not just running out of fuel.
As I have said before.

All new newer cars with fuel injection mount the fuel pump in the fuel tank. This is done because with the higher pressures required, the pumps do run hotter. By mounting them in the tank the liquid fuel provides needed cooling.
It is better to keep the car more full than empty so as not to shorten the life of the pump.


Dave

Retired ASE Master Tech

 

I'll be more than happy to report when my pump fails so you can say "I told you so!".

I would think a gallon of fuel is more than enough to keep the pump cool and many pumps sit outside of a fuel tank and never overheat. What is the engineered operating temperature range of an in tank automotive fuel pump BTW?

 

I get too nervious. I think I've seen the low fuel light twice in one year. I've put 20 gallons in my wifes minivan once. It holds 20.0 gallons.

How about: How many quarts of oil you've put in a car to get it up to the full mark?

 

The lowest I've gone is 16 miles until Empty. I'd be terrified if I got to 0!

 

I don't mess with it in the Fiesta. It seems that last 50mi goes really fast.

In the Prius it tells you that you are empty with about 9 gallons out of 11 gone so you can drive around for a few days on E but I generally fill up around 9.5 in it and between 9.5 and 10 in the Fiesta.

 

to be honest, I have yet to hit 0 to empty. came close but having worked with computers for 35+ years, I do not trust the accuracy. Most at a fill-up was 10.68 gallons, but usually average 9-9.6 in decent weather. Winter I never let the tank get under 1/4 full.

might be because a human has still had their grubby fingers in the code. <shrug> also, sure as heck I try something like that, Murphys Law kicks in and I end up stranded at the worst possible time.

 

I believe most modern fuel systems circulate their fuel continuously so the pump runs all the time pretty much at a steady state, thus generating a constant pressure for injectors and a mostly constant load on the pump whether you are cruising at 60mph or going WOT. Pumps do work and do generate heat. Any give amount of fuel can sink only a certain amount of heat and can dissipate that heat at some certain rate. Maybe one gallon can dissipate the all the heat generated by the pump as it sits in the tank or is circulated to the injector system and back but I don't know. Certainly more fuel could sink more heat and have a longer time to dissipate it.....

I too, would like to know what the operating temp of the pump is as well as how much heat it generates. But since I don't know the fuel heat dissipation rate it really won't do much good. From a purely observational point of view why on earth would engineers go to the effort of placing the pump in the tank and providing it with electrical connections and fuel line hookups, and the associated access panels and seals, when it would be easier to put it and it's connections on the outside like was done for so many years prior. I suppose it might be a noise reduction thing but I kind doubt that was the only reason and question how effective that would be compared to other options.

Personally I am guilty of running my tank dry quite regularly, and have coasted into a gas station on more than one occasion. In the last 400k miles or so I have had one pump failure (and I am not 100% sure it was a pump failure but I replaced it anyway)...I guess it sure wouldn't hurt the pump to just keep a few gallons of gas in the tank, but I haven't seen a rash of pump failures with my run it bone dry strategy either....I will say it does get very slightly louder when the pump is exposed.

 

The fuel pump on my Escort went out at 80-something-thousand miles. I figured it was the cheap gas I was using but this one guy said the same thing about the fuel pump that D1JL said and also claimed that I should fill up at half-a-tank. I don't think I'll ever really know what the cause was.

Anyway, I wouldn't know my miles to empty since I have an S model and it doesn't tell you those types of things. However, I find myself refueling at 300 miles regardless of what the gauge says. It's just habit since no car I had before would go much past 300 on a tank.

 

Even the Car Talk guys, Click and Clack recommend not letting the tank go dry. If they say so then its good for me.

 

yea by no means would i make a habit out of this i was just curious if anyone pushed it in any kind of situation i mean we all get in tight spots from time to time. On the opposite side then when is a good time to fill up? i generally fill up with around 15 miles till E is that an ok range to fill up at?

 

I usually fill up at the 1/4 mark or when the low fuel warning first comes on.

 

I think that the assertion that a fuel pump will overheat if the fuel level is low is an "old wives tale". The fuel pump is cooled by the fuel that flows through it, not by being immersed. And remember that the pump flows FAR in excess of what is being used, with the remainder being returned to the tank continuously. The heat sink theory is baloney, too. With the fuel sloshing around the vast expanse of the tank, it will cool easily.

As far as driving past the "0" miles display, I've driven at least 50 miles past 0, and still only filled up 11.7 gallons. So even then, there was plenty of gas left to "cool" the pump

 

Ditto to Reddog99's logic. If (and I think that's a big if) the pump needs cooling, the fuel sloshing around and the fuel traveling to and from the engine will do that. On the other hand I do think it is a really bad idea to actually run out of gas. That can't be good for either the pump or injectors since the fuel is bound to provide some amount of lubrication.

I do not know why the pump is in the tank but I would guess it has to do with easier self-priming rather than cooling. Self-priming would not be a problem on a motorcycle since the pump is below the tank.

 

This should settle the argument and I stand corrected

Today's fuel pumps are immersed in the tank for a good reason and need fuel surrounding it. Two main reasons. Prevent vapor lock and prevent fire hazard by virtue of the fact that liquid fuel is not combustible.
Rather than paraphrase I'll "lift" the article from

Fuel pump - Wikipedia, the free encyclopedia

In many modern cars the fuel pump is usually electric and located inside the fuel tank. The pump creates positive pressure in the fuel lines, pushing the gasoline to the engine. The higher gasoline pressure raises the boiling point. Placing the pump in the tank puts the component least likely to handle gasoline vapor well (the pump itself) farthest from the engine, submersed in cool liquid. Another benefit to placing the pump inside the tank is that it is less likely to start a fire. Though electrical components (such as a fuel pump) can spark and ignite fuel vapors, liquid fuel will not explode (see explosive limit) and therefore submerging the pump in the tank is one of the safest places to put it. In most cars, the fuel pump delivers a constant flow of gasoline to the engine; fuel not used is returned to the tank. This further reduces the chance of the fuel boiling, since it is never kept close to the hot engine for too long.
The ignition switch does not carry the power to the fuel pump;....

I previously stated that Tom & Ray of Car Talk said its not good to run your tank to empty. I stand corrected. They don't seem to think it makes a difference. See

Is it really OK to let your gas tank run down to empty? - NWautos

Also from
Running on Empty - ABC News

By JOHN STOSSEL
June 5, 2008


So why do cars say "empty" when there's still gas left? Ford said it's about providing a "comfort zone" for the driver -- you don't want to have the light go on and all of a sudden, you're dry. GM said that customers in the United States want that reserve, and they provide it. Chrysler said some drivers, German customers, for example, want to know exactly how much gas is in the tank, but Americans like to have a buffer.

However, do a Google search titled "is it safe to run a gas tank to empty" and you will see testimony from many saying its not a good idea.

I'll continue to error on the side of safety. Especially since a fuel pump can cost between $400 and $1000 repair. Is it worth it?

 

I bow to your greatness Norm201. Great investigative work.

 

Thank you kind sir.

 

i have had a fuel pump go on me due to running it dry. it was because the pump was straining so hard to get enough fuel to maintain pressure and it burnt out. it was completely my fault (i knew better than to let it get that low), and not something that i would expect to happen on a typical, non-modified car. i only mention it because it IS possible for this to happen. on the average car though, i wouldn't worry about it.

i never let my tank get that low though, just because i don't want to run out of gas. i'm not concerned at all that it's going to burn the pump. and if it does end up burning out the pump, it will be long after i've gotten rid of the car lol

 

Thanks for posting that Norm. I think you're being overly cautious but, to each their own. I'll continue filling up when there is about a gallon left and know that I'm probably well within the engineered design spec of safety relative to the pump.

 

Getting back to the thread... I routinely run 10-15 miles past the "0 DTE" reading. That whole measurement is suspect since, in my car, the number ALWAYS drops from about "17 DTE" to zero in 2-3 miles. Where'd those missing 15 go?? And I still can only get 10.5 or so gallons in.