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Running close to empty will ruin fuel pump?

For every car I've ever owned, I've always waited until the low fuel light came on or until I was at < 1/8th of a tank of gas to refill. I've never had any problems doing so. The only time I ever make a conscious effort to keep a full tank is in winter.



I was recently told that this puts excessive strain on the fuel pump and can cause premature wear out. Is this the case? If so, what is the lowest amount of gas we should keep in the tank to avoid straining the fuel pump?
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Comments

  • edited November 2009
    The fuel pump is submerged in the gas tank, and the gasoline serves as coolant for the pump. Low gasoline level can lead to overheating of the pump.

    I don't like to let my car's gas tanks get below 1/4.

    Keeping the tank closer to full also helps minimize condensation of water in the tank.
  • edited November 2009

    The fuel in your tank helps to cool the electric fuel pump, which frequently generates a fair amount of heat as it runs. Thus, chronically running the car with a very low level of fuel in the tank does expose the pump to more heat than if it was run with a higher level of gas in the tank. Heat does take its toll on most things, including electric motors.

    All of this leads me to the inevitable question:
    Why not just fill the tank sooner, rather than always waiting until the last possible moment? If you made it a practice to fill the tank every time that it fell to the 1/4 mark, you would not spend any more time in gas stations than if you consciously decide to wait until it is almost empty.
  • edited November 2009
    Thanks for the info.

    I drive about 280 miles a week and have a gas tank that can get me about 300 miles. It's a lot easier to only have to fuel up once a week vs. twice. I was also completely unaware that I was causing damage to my car; I re-read my owner's manual and it made no mention of the fuel pump. I've also never had to get one replaced after several decades of driving.

    Is 1/4 tank considered the lowest level one can let the tank run down to?
  • edited November 2009
    Others will disagree with this, and it depends on the car that you have. Mine, like many, has a small bucket around the pump that keeps it cooled by gasoline, even if the tank is very very low. The pump will only be damaged if you actually run out of gas. As long as there is a gallon still in the tank when you fill up, you will be okay.
  • edited November 2009
    If you wait for the light then usually most cars have 2gallons+ left.

    My wife has done this on all her cars run 150k-200k in her ownership and no fuel related problems.
  • edited November 2009
    I see your point in running from full to close to empty rather than make frequent fuel stops. What kills the fuel pumps prematurely are drivers that run near empty and then fill with a $5 or 10 and therefore are constantly running without much fuel in the tank.

    The fuel pump and tank designs differ and some cars are more prone to heat related fuel pump failures than other makes and models. As long as you fill your tank you aren't running on low fuel too much and your fuel pumps have not been problems for you. Yet, refilling the car at 1/4 tank most of the time reduces your risk even further.
  • edited November 2009
    People like to have explainations for events and the "low fuel level" damages pumps satisfies this desire for an explaniation. The story keeps getting repeated from person to person and it becomes much easier to get on the band wagon than say"is any evidience of any type other than anecdocial available?"

    You will get "low fuel level causes check engine lights " also.

    I would be spending all my time on the side of the road (or with a check engine light on) if the claim was true.
  • edited November 2009
    There is lots of "urban legend" stuff surrounding this subject.. In most tank / pump designs, the actual pump is mounted high in the tank and is only submerged when the tank is full or nearly so. Since the fuel system constantly is returning excess fuel to the tank in a closed loop constant pressure system, the fuel flowing through the pump keeps it cool, if indeed it needs to be kept cool..This whole argument depends on the fallacy that in-tank fuel pumps are somehow subject to overheating when in fact I don't believe that's the case...

    Overheating fuel pumps inside a closed gasoline tank are NOT a design feature that is built into these pumps. They don't fail because they overheated. They fail because they wore out or the flex-lines that connect them inside the tank rupture and pressure is lost. Once fuel pressure is lost, the engine and fuel pump are shut down long before the pump "burns up"...

  • edited November 2009
    Just a slight correction here. Most fuel systems (being made now) are now return-less systems, so there is no constant circulation.
    I do agree that fuel pumps don't overheat or fail due to low fuel levels. I do know that they can fail due to no fuel conditions. I have seen older pumps that couldn't handle the stress when run dry. I have also seen the fuel pump fuse blown when someone ran out of gas. Of course, there are many more examples where running dry did not cause any failure.
  • edited November 2009
    The pump will only be harmed to some degree if the fuel level drops low enough to cause symptoms such as bucking and jerking and it make take a number of episodes like this to actually kill a pump. A one time deal won't do it.

    As long as there is enough gas in the tank to keep the pump filled (no bucking of course) then simply running the level down low will hurt nothing.
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