Running on empty damaging to fuel pump?

sharx35 wrote:

less than 1/4 a tank of gas.

=== I asked the same question. After reviewing all the answers, I now run the gauge closer to empty. One responder I trust regularly ran the gauge to empty or below the empty line, with no ill effects over several hundred thousand miles. Regarding an immersion pump, yes, the pump is in the fuel tank, but with the fuel injection system, excess fuel bled off by the pressure regulator on the fuel rail goes back to the tank and bathes and cools the fuel pump. Seems what could ruin the electric fuel pump within mere moments is running dry since drawing in fuel lubricates the internal gears. (although I'm not sure how you could be using the fuel pump if you were completely out of gas - the engine wouldn't be running - perhaps by repetitive starting attempts) There was some concern the pump could be sucking air momentarily on corners with very low fuel levels and you'd never know it. There are baffles to minimize this effect, but if you're going to run really low, best to be in a straight line on the highway headed for the next gas station. Seems some people run until the low fuel level warning light comes on and then fill up but that seems unnecessarily risky. For people who don't live in dry climates, there is concern that low fuel levels mean more air in the tank which can allow moisture condensation which is neither good for the fuel nor the tank. While the fuel does recirculate through the fuel injection back to the tank, it may be useful to run the tank lower to fill with all fresh fuel. My owners manual suggest it is a good idea to keep the level above one quarter tank, but doesn't say whether that is to avoid running out of gas or there is also some mechanical benefit. My conclusion was that the pump cools from the return line right at the pump and it is OK in my Southern California area to run the tank closer to empty. These days I'm usually filling up with apx. 1/8 tank remaining on the gauge, With 18.5 US gallon capacity, last time it took 12.8 gallons, so roughly five gallons remaining which should be fine. I track miles planned versus the trip odometer miles used to determine when to fill up next in addition to the gauge.

I use the fuel light to fill up. That's around 1/8 tank.

Some said to keep a 1/4 to help cooling, not only to help the fuel pump but to lessen the chance of vapor lock. In addition, it's safer to keep the pump submerged in the fuel than to leave it exposed to vapor in case of accidents, because liquid fuel doesn't burn. However, I think the pump is already exposed by 1/4 tank anyway.

less than 1/4 a tank of gas.

The reason I always fill up when I get down to 1/4 tank has nothing to do with the fuel pump...never thought about it. but as you drain the tank, there's surely scuzz toward the bottom (sediment and stuff that's not filtered out at the gas pump) and so I try to keep the crapola suspended in lots of fuel. I'd hate to have to replace a fuel filter just because I let the gas in the tank get too low. And I've never run out of gas either.

Undoubtedly, keeping fuel level above 1/4 is good, common sense. Certainly no harm in keeping tank above 1/4.

Just anecdotal evidence on my part, however in 42 years of driving and running down to fumes on many occasions I have never had a fuel related issue that could even be remotely connected to running the tanks to almost dry.

As far as keeping the skuzzy stuff suspended in lots of fuel my way never allows it to build up :)

You name it and I have probably owned one if it is/was a main stream brand car.

AFAIK, ALL Toyotas have immersed fuel pumps.

The fuel cools the pump, therefore, running under about 1/3 exposes the pump and causes it to run hotter.

Also, the fuel keeps the seals wet and keeps them from falling apart. I had to replace a perfectly good *pump* because the seals were shot... to the tune of $475...