Most electric motors operate just fine with the parts you mention dry.
Most electric motors operate just fine with the parts you mention dry
That is true, but most electric motors don't operate in an explosive environment with a solvent cleaning off the lubrication.The gas a gas pump is submersed in helps lubricate and cool the pump. Doing this too often can prematurely burn out a gas pump.
Most electric motors operate just fine with the parts you mention dry.
Not quite. Larger motors run at slower RPMs and have sealed, lubed bearings. Small motors (blower fan, etc) have bushings which may be made of Oilite or lubed by a felt pad, grease pocket, and so on and these motors also turn at comparatively slow speeds.
Fuel pump motors do not have the benefit of sealed bearings, grease as a lubricant, and low RPMs.
This happened to me. 1996 pontiac sunfire. ran it out of gas once and it was hessitant to start up again, but finally did. ran it out of gas a second time, and the fuel pump decided to surrender. (8yrs old and 195K miles)
I was so sad to not be able to see the vehicle tick over 200K miles, as I loved that car and went everywhere with it. (mexico, south padre, colorado rockies, ect)
No car ever ran out of gas at a convenient time, but there have been plenty that have run out at INconvenient times! I cannot think of one single advantage to allowing a gas tank to run as low as possible. I can thionk of a lot of reasons not to. Those reasons have already been mentioned by others.
But, the bottom line is, some people simply like to push their luck. Triedaq pointed out two, and there are many otheres. We’ve heard from people running on bald tires, totally worn out brakes. We even heard from someone that did a failed patch job on a brake line and was driving around routinely refilling his brake fluid reservoir!
Years ago my son came by the shop to get gas money and left the truck running. By the time he got back out to it it had run out of gas.
I went to my stock room and pulled out a new, at the time $200.00 fuel pump to show him why not. Showing him price, complexity of repair, and the electric motor needing to be submersed.
" You mean I just burned up the pump ?" he inquired with big eyes.
“Not this once” I said, " But you do that several more times and it WILL be toast."
Adding to that lesson I made him walk the half mile to the station with a five gallon can.
You ask me to name one person who has needed to replace a fuel pump because of running out of gas. Her name is Rina. I don’t remember her last name. She was my girlfriend back in 1993 and she drove a Plymouth of some kind. She had a fuel pump go bad and her mechanic told her is was because she let the fuel get so low that it damaged the fuel pump.
Long term use of a partially clogged fuel filter can also shorten the pump’s life. The car may not even have any noticeable symptoms either. Logic would dictate that a clogged filter should cause the engine to buck, even in a subtle manner, but that’s not always the case as I’ve seen engines run fine with badly clogged filters.
You will not burn out your fuel pump by running the gas tank low or out of fuel because if there is any fuel in the pump then the pump will be no hotter than the fuel. Once Upon A Time this was possible to burn out the pump because the pump was on any time the ignition was on. The pump could run without fuel and overheat. Modern cars and trucks will only run the fuel pump for 15 to 30 seconds after the ignition is turned on. If the engine does not start the pump is turned off to protect it. This is why after running out of gas if your engine does not readily start you must turn the car all the way off a few seconds and retry so the fuel pump can run and try to reprime the system.
I have to respectfully disagree with that assertion. Running the fuel level low enough to reach the point of engine bucking and stalling can damage the pump. It does not necessarily burn it up but does create undue bushing wear (especially on the impeller end) and most importantly; those seconds of air inhalation will chew up the commutator and brushes pretty quickly. Eventually the pump dies although burned up may not be the proper description.
A one time event is not a big deal but having this occur a dozen times may well be.
As to pumps running whenever the ignition was on I could add this. Federal regulations have prohibited the use of constantly running pumps for 40 years or so and back in the old days most electric pumps were of the diaphragm type, not the rotary type used in FI systems. A diaphragm pump has no bushings or brushes and will not be harmed by pumping air. In essence, it’s an acquarium pump.
An older rotary pump used on carbureted cars also does not turn at the near the RPMs a modern FI pump does and does not have to contend with high pressure either.
One reason to keep the gas tank full is to avoid corrosion. If the tank is near empty, then the top of the tank is full of warm, moist air; then when the temperature cools, say at night, the water vapor in the air will condense onto the inside surface of the tank. This can cause rust, and rust if it breaks off and falls into the gasoline will eventually clog either the pump or the fuel filter. If the tank is full, there is less air, and less surface area for water vapor to condense.
Also, thecondensed water vapor may drip into the gasoline, and the more gasoline there is to dilute the water, the better probably.
Another consideration is that if indeed the fuel in the tank is polluted with particles of rust or whatever else might pollute the gasoline, when the tank is low on gas, the concentration of the rust particles is greater, which makes it more likely the rust particles will make their way through the pump and into the fuel filter, hopefully they’d be caught there, clogging it, rather than breaking through and clogging the injectors.
All that said, I’ve never worried about this. I run the tank to close to empty routinely, and never have had any problem. It must be the case that the gas tank and venting system is designed to handle this problem already. Keeping a full tank is not something to lose much sleep about, at least from my experience with the popular econoboxes.
I seem to remember the original caller owned a Volvo. I don’t know about other cars but in this car the fuel pump housing fills itself up with fuel to cool the pump, so no matter how low the fuel gauge is, there is always fuel cooling the pump itself. The pump will cutout when the housing still has fuel in it. This vehicle also has a “miles to empty” feature. On long road trips I regularly run this to 30-40 miles, at which point I can get 17.5 gallons into my 19 gallon tank. Even on the one occasion when it showed zero, there was still 1/2 a gallon in the tank.
I think what bothered the original caller more, is the live-close-to-the-edge aspect of this. Maybe they have gas stations at each corner (and don’t feel constrained by price).
I don’t like to let any of my vehicles get below 1/4 tank, and it’s not for worry about fuel pumps.
For someone with that kind of attitude, let them run out of gas, then when they call you wanting you to pick them up, call them a tow truck and have the tow truck tow them to the gas station at the far end of town, on their dime. After a couple $100+ towing bills, they MIGHT change their minds, but I’d doubt it.