Info: The 1/4 tank to cool your fuel pump myth

Which is a distinct possibility if the "pump would be shaped like a large flat can and be right at the bottom of the tank." in most people's cars.

Just checking to see if THIS will show on TAA

- - - - - - - Contrary to what some believe, it's not necessary to keep your tank at any given level to prevent your fuel pump from "burning out".

Inspection of any pump/sender assy will bear this out. If such were the case, the pump would be shaped like a large flat can and be right at the bottom of the tank.

In fact, you are FAR more likely to burn your pump out prematurely if you have a clogged fuel filter.

It's gas flowing THROUGH the pump that provides the cooling... and on EFI systems that use fuel rail regulators and return lines, the flow can diminish enough to allow the pump to overheat while there is still enough flow to run the engine.

Spike wrote in news: snipped-for-privacy@4ax.com:

I can guarantie that 80% of the ones I replace when asked, tell me they run low on fuel much of the time, as in below a quarter tank. The ones that don`t have far fewer pump problems. Remember the less fuel in the tank the lower volume to shed heat in the summer wether bypassing or not. KB

uh.... I would reckon it would still have a boot on the pickup... and the pickup IS at the bottom, now.

Your gonna start a fight on this one BM. I think its the "suck air and then all of a sudden fuel syndrome" that kills the pump if you run it way low. Think about it, you make a turn the pump sucks air, then you straighten out and it catches fuel again.(lots of strain on impellers.) Its like revving your boat with the prop out of water and then suddenly dropping it in the lake. The prop shear pin will break I bet. (haven't tried it) :)

I do think your right about it not being heat (although I've seen lots of burned wires on bad in-tank pumps. (on GMs).Come to think of it, I don't recall the last Ford pump that's has failed, lots of Chevy's though.

well hell nell....explain to me with all this heat and burnin up the tank just dont EXPLODE!i never understood and still dont how you can run an electric motor in a gas tank!!??!!especially on FUMES!!

What i SAID was the fuel running through it cools it, doesnt have to have fuel around it.

Obviously running it dry is NOT good for it.

And no the shear pin on a boat prop doesnt break that easy.

Well, if you cant figger that out, I prolly cant explain it... unless you understand why an engine wont fire when it's flooded.

Didnt you ever see a ... never mind,, if I describe it, someone will "jack- ass" it.

;)

LOL Well if you're gonna be picky about it... : 0 )

IMHO, your assumption is correct..... I can't recall how many times I have replaced a long-overdue fuel filter only to see the fuel pump expire within a few short hours.

The techs job gets tough.... he's an asshole because he estimated a fuel pump based on filter condition... customer declines the pump and lives happily for a long time.... or, he's an asshole because he replaced the filter and it looks like the concern was the fuel pump all along..... I keep my mask and handgun in the bottom drawer of my toolbox... no self respecting thief should leave home without them...

Running a tank low wont hurt the pump.... running the pump dry, however....

With any "aromatic" such as gasoline, we have UEL and LEL (upper explosive limits and lower explosive limits). In one instance, there are insufficient fumes to ignite... in the other, there is insufficient oxygen....

We should always be careful of assumptions when it comes to a device or system that has been "engineered".... for all of these, there is a purpose. The only difference lies between those things engineered well and those things engineered poorly.

hey Jim, in John Q Publics eyes, all stealership mechanics are thieves and rectal orifices that are just waiting to hit them with a $800 bill for a simple misfire. they don't want to hear that it is the dealership that sets the price, charges list for parts, and that the mechanic only sees $75-80 of that $800, all they know is that you are a crook.

however....

And here all along I thought it was just the service writers. Damn!

What you say about the fuel running through the pump providing the cooling is true....but you left out the rest of the story. Systems with pressure regulators and return lines constantly circulate fuel from the tank to the injector rail and back to the tank (the excess that is not actually injected into the intake). All this pumping heats the fuel. If you have a lot of fuel in the tank, you have a very large heat sink and the fuel stabilizes at a relatively low temperature. If you only have a little fuel in the tank, all this circulating can significantly heat up the fuel in the tank and shorten the life of the pump (assuming you repeatedly run the tank low). This is the major reasons manufacturers are moving toward returnless systems.

Ed

There is no oxygen in the tank (or at least not enough to provide a combustible mixture).

Ed

-to be PERFECTLY clear for the non-technical, here, it isnt the pumping that heats the fuel, it's the REPEATED TRIPS through the engine fuel rail. (tho I guess a partially clogged filter would reduce those trips and maybe not heat the fuel as much... but check with a thermodynamic engineer physicist, I bet that more hotter fuel flowing cools better than less cooler fuel.)

- The 'returnless' is a bit of a misnomer, the 'return' is in the tank.

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Hey, old geezer! Left a message for you way back on oct 9th about the wood block thing. The thread was fuel leaks. I thought it would come to the front when I added something but guess this forum doesn't work that way. Anyway, I just came back to the site after getting mad back then. Read your bygones response. Thanks. Bygones it is! Peace from kind of an old geezer. I do stand corrected for not specifying what I meant by "blocks". Sorry for my language also. Doug

Backyard, My message back then hasn't appeared. Must have goofed. Anyway, this was the gist of it.

non de problemo... whatever gets the blood circulating is all good!

As far as the message not appearing according to date, that's a function of 'VIEW' on most forums and newsreaders.... though not always available, you can usually specify that you see the posts sorted by date, not as part of a thread.

The default however, is threaded view... TAA may vary.