Re: In-the-tank fuel pumps cause death and destruction

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The gas heaters were mounted above the fuel tank and had their own electric fuel pump. H
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wrote:

Guess the two that I'd seen on had identical aftermarket units put on then. Luckily I've not "had the pleasure" of working on an old Beetle in over 15 years. :-)
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Don't forget Corvairs had gas heaters also.
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wrote:

No, all gas heaters were mounted above the fuel tanks and had their own small electric fuel pu to spray the fuel into the fire-box. Basically a low presure fuel injector.
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On Mon, 01 Nov 2004 19:26:32 -0500, snipped-for-privacy@sny.der.on.ca wrote:

No..... The two that I had experience with had no electrical fuel pump. Which is why I mentioned them.
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My '64 Corvair that I had, the fuel line had a tee in it so the engine fuel pump supplied both the heater and the engine.
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Where were the heaters mounted? H
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wrote:

About 6" above and rear of the pedals. Personally thought it was a stupid design, but then again the Beetles were never the greatest for heat I'd heard.
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I'm not sure what you saw, but that wasn't a gas heater. Gas heaters were mounted inside and parallel to the left front quarter panel, under the front deck lid. They were/are roughly the shape and size of an old Electolux cannister vacuum.
Personally thought it was a

Actually the heaters were ok but the defrosters were horrible. Add a gas heater and you could almost cook a roast in one.:-) Btw, I still have two, a '62 sunroof and a '69 vert. H
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wrote:

I'll have to take your word on that, despite how worked & was used as.
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Bill Putney wrote:

wouldn't the arcing be only where the actual motor assembly would be? could this not be a sealed unit? Would you even want gas in there? I would think gas does a poor job of lubrication - you'd have some kind of grease in the actual motor assembly, wouldn't you?
the gears that pump the gasoline won't be arcing...
fwiw, my fish tank pump uses a sealed pump assy with a magnetic drive assembly - no chance of water touching the electrical parts.
Ray
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Ray wrote:

Hey hey hey! One question at a time! 8^)
Actually, the commutation (brushes) are in the fuel that is flowing thru the pump. The motor armature, magnets, pumping elements, and commutator are in the same compartment swimmimg/spinning in the fuel.
> I

Nope. The "bearings" in the ones I worked with (supplied to GM and Ford) were simply holes molded into the plastic end caps of the motors - again - in fuel. That is typical of the modern automotive fuel pump. One reason fuel pumps can become noisy is that those plastic bushings wear (actually, usually the metal shafts wear a lot faster than the plastic due to abrassive glass fibers in the plastic) and the armature starts rattling around.

No - but there are brushes.

Magnetic drives are a great way of eliminating rotating seals, but that magnetic drive wouldn't transmit the torque needed to develop 60-90 psi. 8^)
Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my adddress with the letter 'x')
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The intank fuel pumps I've worked on are totally wet, with fuel flowing right through the motor.

And none of the fuel pumps I've worked on were gear pumps.

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I try to keep gas in my fuel tank, mainly to avoid the inconvenience of running out of gas. I guess I get the added benefit of not having my fuel pump explode. It actually works out not too bad.
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It also increases the longetivity of your pump as the gas is it's cooling system. H
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this also means you should keep your tank level from getting too low. Otherwise you can shorten the life of your pump. -------------- Alex
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Alex Rodriguez wrote:

Another urban legend.
Matt
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On Tue, 02 Nov 2004 16:53:18 -0500, Matt Whiting

Not totally. Running the pump VERY low on fuel reduces cooling and lubrication and CAN hasten the pump's demise.
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snipped-for-privacy@sny.der.on.ca wrote:

Absolutely not on lubrication. It is impossible not to have gasoline in the pump at the bearings if the vehicle is running off of fuel from the pump since the bearings (more accurately, bushings in almost all consumer vehicles)are within the internal pump volume (the shaft and bearings are surrounded by the fuel as it flows thru the pump. If there's no gasoline at the bearings, neither is there fuel getting to the engine, i.e., the engine will not run, and most likely neither will the pump for very long at all (and that's not "low" in fuel - that's "out of" fuel). The bearings running dry or even slightly low is not a credible situation at all - not even at the point that the engine cuts off due to your "running out of gas" (at which time the pump still is full of fuel).
As far as the cooling aspect, yeah - you might have that on a technicality, but you do have a steady cool volume of the fuel running thru the complete internals of the pump/motor assy. So, probably the outside surface of the pump (case and magnets, which are on the inside surface of the case) will rise a few degrees, but the insides (armature, brushes, bearings/bushings) would rise *very* little (due to the volume flow rate of ambient temperature fluid that bathes those components. I doubt that those thermal effects are at all significant in pump life.
IMO...
Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my adddress with the letter 'x')
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Bill Putney wrote:

It is amazing how these myths get started whenever there is a change in technology and just refuse to die. I wonder how the old style pumps that were connected to the engine block ever managed to stay cool! :-)
People don't understand that electric motors can be designed to run at fairly high temps. If the above assertion were true their would be a lot more electric fuel pump failures as I know a lot of people who run low on gas, and even out of gas, fairly frequently. It is almost the same things as the exploding gas tank myth. Even people who won't accept a logical technical argument have to admit that is just isn't happening in the real world. There is a reason for that!
Matt
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