Re: Repeatedly Running On A Low Tank?
 

jim beam wrote:
> Bill Putney wrote:

>> It would be neat to see an article reporting the actual temp. increase
>> measured inside in the tank and inside the pump with full tank vs.
>> half full down to 2 or 3 gallons total in the tank from someone having
>> instrumented a "typical" vehicle. With all the warnings about it,
>> you'd think *someone* would have published such a study. Why is that
>> not the case? Makes me suspicious of the warnings that are repeated
>> by people who haven't a clue.
>
> no! say that can't be so!

:)

>> Telltale signs of an urban legend maybe?
>
> and without it, there would be 90% less usenet traffic.

Well - that, global warming, and K&N air filters. :)

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

Re: Repeatedly Running On A Low Tank?
 

ScottM wrote:
> "Bill Putney" <bptn@kinez.net> wrote in message
> news:6ai0kvF37k2jlU1@mid.individual.net...
>> Don't Taze Me, Bro! wrote:
>>> Consider filling up your tank and not letting it drop below halfway,
>>> instead of keeping it on low and only putting in 2 gallons here and
>>> there...
>>>
>>> http://www.foxnews.com/story/0,2933,361347,00.html
>>>
>>> Not because you could run out of gas and get stranded but because
>>> repeatedly running on low tends to ruin the fuel pump.
>> I see that thing about running low on fuel damaging fuel pumps posted all
>> over the internet, but personally I think that's total b.s.
>>
>> All the critical parts in the fuel pump - bearings (bushings), armature,
>> brushes/commutator, pumping elements (vanes, rotors, or rollers) - are
>> constantly bathed in the fuel as it flows thru the pump. That lubricates
>> and cools the parts regardless of fuel level in the tank.
>>
>> With regulator bypass pumping/circulation that modern cars have, there is
>> full volume of fuel going thru the pump at all times it is running
>> regardless of engine demand. The only effect of low fuel in the tank is a
>> slight temperature rise of the volume of fuel in the tank (due to same
>> electrical power dissipated in the pump being absorbed by less mass of
>> fuel), and that rise will be very small - power used by fuel pump is
>> small - temperature rise of the fuel in the tank and the tank itself will
>> be very small - lots of mass compared to the power being dissipated.
>>
>> *BUT* - again - the fuel is constantly flowing thru and around all
>> internal components of the pump whenever it is running providing cooling
>> (unless you actually run out and the engine stops - but that is a
>> different scenario altogether, and even then, the pump will still be full
>> of fuel at that point with a full column of fuel from its lowest end to
>> the fuel rail - only the pickup will be filled with air, and there won't
>> be any flow - and most cars turn the pump off when the computer senses
>> that the engine is no longer running).
>>
>> If anyone wants to argue this, be sure of your facts beforehand - I used
>> to design automotive fuel pump components.
>>
>> Bill Putney
>> (To reply by e-mail, replace the last letter of the alphabet in my address
>> with the letter 'x')
>
> Ive seen it happen many times but only on Chevys. Of course it could be
> coincidence but I don't think so. "I thought I ran out of gas because it was
> really low but I put gas in it and it still wont start" <<<<like that.
>
> p.s. you didn't design Chevy fuel pump components did you? ;)

Actually - yes. But we'd have to know which pump/platform.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

Re: Repeatedly Running On A Low Tank?
 

Retired VIP wrote:

> Are you saying that it is okay for a reporter to publish incorrect
> information just as long as he believes it? Or are you saying that it
> is okay for a reporter to publish his opinion as fact? What ever
> happened to checking your facts before publishing?

Pfft! That's old school.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

Re: Repeatedly Running On A Low Tank?
 

Bill Putney wrote:
> jim beam wrote:
>> Bill Putney wrote:
>>> jim beam wrote:
>
>>>> 1. an electric motor with very limited load doesn't get very hot -
>>>> certainly not hot enough to require liquid cooling.
>>>
>>> About 75 watts. Not a lot, but not nothing either. It does indeed
>>> require cooling (and lubrication) by the liquid going thru it.
>>
>> it can take advantage of it, but it doesn't /need/ it. windshield
>> motors are higher wattage and have no cooling other than ambient.
>>
>>
>>> Without that, indeed problems would quickly develop.
>>
>> well, it's not coils, bearing or commutator/brush problems. and it's
>> only pump problems on gear or scroll types.
>
> You are talking to the guy who designed and power limit-tested the
> EMI/RFI coils on a certain GM gerotor pump. Believe me: The wire was
> sized minimally for reliable life in fuel (for cooling) - 24 ga. solid
> copper magnet wire carrying approx. 5 amps. I also designed the plastic
> brush holder which also served as the motor/pump end cap. The "bearing"
> (bushing) on that end is merely a hole precision-molded into the
> plastic. The fuel is needed for lubrication for the bearings and shaft
> to last a reasonable period without the armature rattling around and
> crashing into the magnets. With fuel, bearing/shaft life is reasonable.
> Without fuel, it would not be. You would not get away with a metal
> shaft/plastic bushing bearing design on a windshield wiper motor -
> because of the lubrication, you can on a fuel pump.
>
> The powders that go into the molded brushes are specifically designed
> for use in gasoline. You would *not* use the same materials in the
> brushes for use in gasoline as for use in air. High current-density
> brushes (like in starter motors) have a *lot* of copper in them. Fuel
> pump brushes are almost pure carbon/graphite.
>
>>> Nice also to keep the two missing ingredient for explosions - oxygen
>>> and fuel vapors - away from the arcing of the brushes/commuator, eh?
>>>
>>>> it's harder yet for him to understand that
>>>>
>>>> 2. modern gasoline fuel injection pumps are typically "turbine"
>>>> types, and the impeller doesn't wear, much like the water pump in
>>>> the radiator circuit.
>>>
>>> Maybe typically, but there are other types in common use - roller
>>> vane (at a noise disadvantage), and gerotor, which most of my
>>> experience is with (some GM platforms). I don't know if the industry
>>> has migrated mostly to one type since I left it 7 years ago, but I
>>> suspect there is still some mix of types.
>>
>> may well be, but this was posted to a honda forum and i'm responding
>> to that: honda use turbine type according to the service manuals i have.
>
>>>> with old style pumps that used gear or scrolling vane pumping,
>>>> lubrication, and limited life, was indeed an issue. modern pumps
>>>> such as those used by honda last as long as the motor brushes,
>>>> submerged or not.
>
> The motor itself (bearings, brushes, armature) would not last long
> without the fuel. The turbine fan of course has no solid-to-solid
> rubbing/wear so I'll give you that.
>
>>> I guess what you're saying is that Honda uses mostly or totally
>>> turbine pumps?
>>
>> apparently so.
>>
>> the point is that the old fashioned generalizations of 30 years past
>> are ignorant irrational b.s. for fuel pumps, just like all the
>> ignorant irrational b.s. you get for oil change intervals. back in
>> the 50's, oils were inferior and a 3k mile oil change interval was a
>> good idea. today, with better combustion technology, better materials
>> and better oil formulation, you can easily, reliably, have a 10k mile
>> oil change for some cars, and yet we have ignorant irrational
>> bullshitters falling over themselves to waste their money and bleat at
>> anyone who dares bring a little updated fact into the room.
>
> In general you may be right. However, there are some specific motors in
> very recent years that are extremely sensitive (in a negative way) to
> oil changes much beyond 3000 miles. Examples: Chrysler 2.7L, certain
> Toyota engines, and I believe certain Honda engines. Try running those
> on 10k miles change intervals, and they will totally sludge up and fail
> before 100k miles (typically 60-80k miles). I know almost nothing of
> the Toyota and Honda problems beyond what I read, but I am more familiar
> with the Chrysler 2.7L and its sludge/failure problems.
>
> As for running pump with fuel low in the tank, I was glad to see Ray O.
> point out that many pumps are actually positioned very high in the tank
> so that it is impractical to keep the fuel high enough to guarantee that
> they're submerged all the time. I suspected as much, but wasn't sure,
> so I kept quiet on that point - until today.
>
>> i understand that you cant force dumb people to be smart, but you can
>> sure encourage them to be silent!
>
> Bill Putney
> (To reply by e-mail, replace the last letter of the alphabet in my
> address with the letter 'x')


while informative, there's nothing new in what you say. the vast
majority of detroit's r&d over the last 20+ years has been into life
limitation, and everything you describe is entirely a part of that
process. the japanese otoh don't haven't had the same manufacturing
objectives, or at least, if they do have an end life in mind, it's an
order of magnitude further out than detroit's. [i think japanese intent
is to simply *bore* you into new sales with gross reliability rather
than bankrupt and disillusion which is how we do it.]

i think attributing detroit's faults to japanese vehicles is like
punishing your daughter because you caught your son smoking - somewhat
unjustified.

Re: Repeatedly Running On A Low Tank?
 

hachiroku wrote:
> On Mon, 02 Jun 2008 21:40:31 -0700, jim beam wrote:
>
>>>>> fuel cooled, too, but the difference was they were bathed in fuel at
>>>>> all times, not just with fuel passing through.
>>>>>
>>>>> As usual, rules of thumb don't wash with you. I keep the pump
>>>>> covered.
>>>> as usual, logic is an alien concept for you. tell me, have you been
>>>> having problems with elephant footprints in your butter again?
>>>
>>> <YAWN>
>>>
>>>
>>>
>> so why do you bother? it's like watching a real-life, but very un-funny
>> homer simpson.
>
> When it comes between listening to you, or a former Toyota Factory
> Service rep, guess who wins?
> (HINT: it's not you!)
>
> You already proved how much you know with your 12,000 mile whether-it-
> needs-it-or-not oil changes...
>

get your facts straight - i'm not "whether-it-needs-it-or-not", that's
you with your 3k mile oil changes.

i've done the testing and /determined/ my change interval. real data
beats superstitious bullshit every time.

Re: Repeatedly Running On A Low Tank?
 

hachiroku wrote:
> On Tue, 03 Jun 2008 06:01:54 -0700, jim beam wrote:
>
>>> About 75 watts. Not a lot, but not nothing either. It does indeed
>>> require cooling (and lubrication) by the liquid going thru it.
>> it can take advantage of it, but it doesn't /need/ it. windshield
>> motors are higher wattage and have no cooling other than ambient.
>
> I would absolutely believe that you drive around with the washer button
> depressed constantly.

eh? what makes the wipers move? do you have a pedal under the dash?


>
> Whew, You're a piece of work...
>

Re: Repeatedly Running On A Low Tank?
 

hachiroku wrote:
> On Tue, 03 Jun 2008 06:01:54 -0700, jim beam wrote:
>
>> a little updated fact into the room.
>>
>> i understand that you cant force dumb people to be smart, but you can
>> sure encourage them to be silent!
>
> So why don't you STFU, then?
>

three replies to the same post? what is it with you???

Re: Repeatedly Running On A Low Tank?
 

C. E. White wrote:
> "Ray O" <rokigawaATtristarassociatesDOTcom> wrote in message
> news:G_adnYO148I_SNnVnZ2dnUVZ_vninZ2d@comcast.com. ..
>
>> I don't remember what I said before, but the danger in burning out the
>> fuel pump is if you let it run dry repeatedly. Toyota electric fuel pumps
>> are cooled and lubricated by the fuel flowing through it, not by the fuel
>> around it. Since it is mounted on top of the tank, where it would only be
>> submerged when the tank is fuel, it wouldn't make sense to have to rely on
>> it being submerged all the time when it would only be submerged when the
>> tank is full. Running with a low tank will not have any measurable effect
>> on fuel pump life.
>
> While it might be mounted throught the top of the tank, I believe in most
> cases the pump is actully near the bottom of the tank. I looked at my shop
> manual for the Camry and it appears that the fuel pump stack is set up so
> that the pump is mounted directly on top of the pick-up sock. This implies
> it is almost always surrounded by some fuel unless level in the tank is very
> low. Here is a picture of a Camry Fuel Pump assembly -
> http://info.rockauto.com/getimage/ge...imageurl=http%
>
> Ed
>
>

why is everyone so hung up on immersion? gasoline isn't exactly the
greatest cooling liquid because it has a low specific heat capacity.
what's important is circulation /within/ the pump, not /without/.

Re: Repeatedly Running On A Low Tank?
 

On Tue, 03 Jun 2008 17:38:05 -0400, C. E. White wrote:

>
> "hachiroku" <Trueno@ae86.GTS> wrote in message
> news:Zwg1k.2161$BV.1695@trndny05...
>> On Tue, 03 Jun 2008 06:49:22 -0400, Bill Putney wrote:
>>
>>>> ...Since it is mounted on top of the tank, where it would only be
>>>> submerged when the tank is fuel,
>>>
>>> Oh man! Now you've got to keep that tank above 3/4 full all the time
>>> to keep from destroying that pump!
>>
>> It's mounted low on the bracket, so 1/3 will probably cover it.
>>
>> But, I keep the tank full as much as possible. I don't want my *new*
>> $375 fuel tank rotting out!
>
> The tank is actually steel? I thought everyone changed to plastic tanks
> years ago.
>
> Ed

Not this car...'88 Supra, still has a metal tank.

Re: Repeatedly Running On A Low Tank?
 

"Craig M" <craig_6444@sbcglobal.net> wrote in message
news:bba1k.4428$jI5.1145@flpi148.ffdc.sbc.com...
>I live on the Gulf coast, and this time of year, we keep our tanks full,
>never know when your going to have to pack up the wife, dogs, clothes, ect
>and make a run for it, still have memories of Rita back in 05 arround here
>in Texas.
> Keep tank full, and eye to the sky.
> "Don't Taze Me, Bro!" <N00One187@NoWhere.Com> wrote in message
> news:%HP0k.6360$%Z1.4068@trnddc05...
>> Consider filling up your tank and not letting it drop below halfway,
>> instead of keeping it on low and only putting in 2 gallons here and
>> there...
>>
>> http://www.foxnews.com/story/0,2933,361347,00.html
>>
>> Not because you could run out of gas and get stranded but because
>> repeatedly running on low tends to ruin the fuel pump.
>>
>
>I'm not going to agree that running the tank below 1/2 will damage a fuel
>pump . Unless a filter is restricting flow and the extra weight or pressure
>in the fuel tank is keeping it fueled. I will agree that its fuel cooled
>and can be damaged by starving it of fuel. (Running out of gas)On electric
>pumps. On another note. My dumbass drunken brother ran my Toyota out of
>fuel. The car is under warranty. The Dealer stated I needed to bring the
>car in and have the fuel filter removed and inspected for metal particles.
>As the fuel pump wasn't supposed to be run dry. If none were found the
>warranty would continue with new filter . If some were found the pump had
>to be replaced or the warranty would not be honored. Because the filter
>would get holes from the particles being in there. And something could
>happened to the engine later. Like the fuel injection system malfunctioning
>later . Or injectors plugging or stuck. The filter had nothing in it.
>Vehicle is good to go.

Re: Repeatedly Running On A Low Tank?
 

None4You wrote:
> "Craig M" <craig_6444@sbcglobal.net> wrote in message
> news:bba1k.4428$jI5.1145@flpi148.ffdc.sbc.com...
>> I live on the Gulf coast, and this time of year, we keep our tanks full,
>> never know when your going to have to pack up the wife, dogs, clothes, ect
>> and make a run for it, still have memories of Rita back in 05 arround here
>> in Texas.
>> Keep tank full, and eye to the sky.
>> "Don't Taze Me, Bro!" <N00One187@NoWhere.Com> wrote in message
>> news:%HP0k.6360$%Z1.4068@trnddc05...
>>> Consider filling up your tank and not letting it drop below halfway,
>>> instead of keeping it on low and only putting in 2 gallons here and
>>> there...
>>>
>>> http://www.foxnews.com/story/0,2933,361347,00.html
>>>
>>> Not because you could run out of gas and get stranded but because
>>> repeatedly running on low tends to ruin the fuel pump.
>>>
>> I'm not going to agree that running the tank below 1/2 will damage a fuel
>> pump . Unless a filter is restricting flow and the extra weight or pressure
>> in the fuel tank is keeping it fueled. I will agree that its fuel cooled
>> and can be damaged by starving it of fuel. (Running out of gas)On electric
>> pumps. On another note. My dumbass drunken brother ran my Toyota out of
>> fuel. The car is under warranty. The Dealer stated I needed to bring the
>> car in and have the fuel filter removed and inspected for metal particles.
>> As the fuel pump wasn't supposed to be run dry. If none were found the
>> warranty would continue with new filter . If some were found the pump had
>> to be replaced or the warranty would not be honored. Because the filter
>> would get holes from the particles being in there. And something could
>> happened to the engine later. Like the fuel injection system malfunctioning
>> later . Or injectors plugging or stuck. The filter had nothing in it.
>> Vehicle is good to go.

of course it is - that whole charade was just the dealer looking to jerk
off toyota or you for the replacement. running dry isn't going to put
holes in a filter - nor will particles. and particles don't suddenly
appear when the tank is dry - they're there all the time.

as for the rest of the pump, running dry tends to stop once the engine
stops running, so it's not like the motor has 100+ hours of non-fueled
running in it. in fact, there was probably more contamination to the
system from disassembly than anything else!

next time, if there is a next time, just gas the thing up and forget
about it.

Re: Repeatedly Running On A Low Tank?
 

Hi!

> (I learned this when I worked as a designer/engineer/manager for a
supplier
> of fuel pump parts to GM/Delphi and Ford/Visteon.

Just out of pure curiosity, did that supplier have a name and can you say
who it was?

William

Re: Repeatedly Running On A Low Tank?
 

"jim beam" <spamvortex@bad.example.net> wrote in message
news:R_Cdnclzg-oCiNvVnZ2dnUVZ_uGdnZ2d@speakeasy.net...
> None4You wrote:
>> "Craig M" <craig_6444@sbcglobal.net> wrote in message
>> news:bba1k.4428$jI5.1145@flpi148.ffdc.sbc.com...
>>> I live on the Gulf coast, and this time of year, we keep our tanks full,
>>> never know when your going to have to pack up the wife, dogs, clothes,
>>> ect and make a run for it, still have memories of Rita back in 05
>>> arround here in Texas.
>>> Keep tank full, and eye to the sky.
>>> "Don't Taze Me, Bro!" <N00One187@NoWhere.Com> wrote in message
>>> news:%HP0k.6360$%Z1.4068@trnddc05...
>>>> Consider filling up your tank and not letting it drop below halfway,
>>>> instead of keeping it on low and only putting in 2 gallons here and
>>>> there...
>>>>
>>>> http://www.foxnews.com/story/0,2933,361347,00.html
>>>>
>>>> Not because you could run out of gas and get stranded but because
>>>> repeatedly running on low tends to ruin the fuel pump.
>>>>
>>> I'm not going to agree that running the tank below 1/2 will damage a
>>> fuel pump . Unless a filter is restricting flow and the extra weight or
>>> pressure in the fuel tank is keeping it fueled. I will agree that its
>>> fuel cooled and can be damaged by starving it of fuel. (Running out of
>>> gas)On electric pumps. On another note. My dumbass drunken brother ran
>>> my Toyota out of fuel. The car is under warranty. The Dealer stated I
>>> needed to bring the car in and have the fuel filter removed and
>>> inspected for metal particles. As the fuel pump wasn't supposed to be
>>> run dry. If none were found the warranty would continue with new filter
>>> . If some were found the pump had to be replaced or the warranty would
>>> not be honored. Because the filter would get holes from the particles
>>> being in there. And something could happened to the engine later. Like
>>> the fuel injection system malfunctioning later . Or injectors plugging
>>> or stuck. The filter had nothing in it. Vehicle is good to go.
>
> of course it is - that whole charade was just the dealer looking to jerk
> off toyota or you for the replacement. running dry isn't going to put
> holes in a filter - nor will particles. and particles don't suddenly
> appear when the tank is dry - they're there all the time.
>
> as for the rest of the pump, running dry tends to stop once the engine
> stops running, so it's not like the motor has 100+ hours of non-fueled
> running in it. in fact, there was probably more contamination to the
> system from disassembly than anything else!
>
>
>Look, the low fuel light stayed on when he ran it out of gas. I couldnt
>figure how to reset it. And under warranty your hands are tied somewhat if
>they threaten to void a warranty. The dealer stated that's because he ran
>it out of gas. Rusty fuel tank metal particles cut a hole in my Goldwing
>fuel filter. And got in my carbs bowls. From vibration and them moving
>around on the tank side of the filter. I could see those as it was a see
>through filter. You don't suppose that could happen in a truck or car.

Re: Repeatedly Running On A Low Tank?
 

"None4You" <None4You@nospam.cya> wrote in message
news:bdydneDxN-FVvtvVnZ2dnUVZ_o_inZ2d@centurytel.net...
>
<snipped>
>>
>>
>>Look, the low fuel light stayed on when he ran it out of gas. I couldnt
>>figure how to reset it. And under warranty your hands are tied somewhat if
>>they threaten to void a warranty. The dealer stated that's because he ran
>>it out of gas. Rusty fuel tank metal particles cut a hole in my Goldwing
>>fuel filter. And got in my carbs bowls. From vibration and them moving
>>around on the tank side of the filter. I could see those as it was a see
>>through filter. You don't suppose that could happen in a truck or car.
>

The low fuel light sensor is separate from the fuel pump and fuel level
sender.

Rusty fuel tank particles will not cut a hole in a Toyota fuel filter
although it could theoretically clog it. It is very unusual for a fuel tank
from the inside out, since the fuel acts as a rust inhibitor. When fuel
tanks rust to the point of perforation, it is generally from the outside in,
not inside out. If there was rust in your Goldwing's fuel tank, I'd guess
that the tank was left empty for a long time or the particles were
introduced from an exterior source like a rusty gas can. Gas stations
generally filter the fuel before delivering it to vehicles, so it is not
likely that the rust came from the gas station.
--

Ray O
(correct punctuation to reply)

Re: Repeatedly Running On A Low Tank?
 

"hachiroku" <Trueno@ae86.GTS> wrote in message
news:Ovg1k.2160$BV.72@trndny05...
> On Tue, 03 Jun 2008 00:04:59 -0500, Ray O wrote:
>
>>> But...But...Ray told me I was in danger of burning out my fuel pump in
>>> my Supra when I got it because the tank had so many holes I had to keep
>>> it below 1/4 tank.
>>>
>>> I trust what Ray says...
>>>
>>>
>> Sorry, Hachi...
>>
>> I don't remember what I said before, but the danger in burning out the
>> fuel pump is if you let it run dry repeatedly. Toyota electric fuel
>> pumps are cooled and lubricated by the fuel flowing through it, not by
>> the fuel around it. Since it is mounted on top of the tank, where it
>> would only be submerged when the tank is fuel, it wouldn't make sense to
>> have to rely on it being submerged all the time when it would only be
>> submerged when the tank is full. Running with a low tank will not have
>> any measurable effect on fuel pump life.
>
> On the Supra it is quite well into the tank, probably an inch or two from
> the bottom. This discussion came up a couple years ago when I still had
> my 'holey' tank and could only run 1/4 tank at a time, and you
> recommended fixing it posthaste as this condition could be detrimental to
> the pump.
>
> Since I take what you say as Gospel ( ;) ), I repaired the tank ASAP
> (Also in an effort to keep at that time $1.78/gallon gas from just
> evaporating into thin air...).
>
> Better safe than sorry, esp @ $199 for an OEM Denso pump!
>

Running the pump dry repeatedly will eventually ruin the pump, but once or
twice probably won't cause a problem. Having holes in the fuel tank can
introduce a lot of moisture in the tank, and of course, the gas fumes that
could escape from the holes are not the best thing to have in a garage.
--

Ray O
(correct punctuation to reply)