If you don't have one....

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The motors inside the pumps indeed had brushes.
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Perhaps not now but they absolutely did back in the 70's and 80's. The brushes wearing out was a common cause of failure.
Even if they did, gasoline requires oxygen

Something has to displace gasoline as the tank emptys. Most every one runs out of gaoline at one time or another and the fuel pump was exposed to air when the tank was low on fuel.
I never really thought about it before, but with

Air displaces gasoline as the tank emptys or the tank would collapse. Unlikely, very true but what keeps the brushes from causing an explosion?
IT'S MAGIC.. ;~)
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The oldest submersed pump system I am familiar with is from the late 80s early 90s GM vehicles using throttle-body injection. Even these systems manitained a constant fuel flow with a return line to the fuel tank. As the return fuel is heated during its round trip, pressure in the tank tends to rise due to increased fuel vapor pressure. You have probably experienced the "poof" of escaping vapor when removing a fuel cap. My understanding is that the pressure inside the tank is largely from fuel vapor rather than air. The natural tendency of the system over time is to exclude air from entering.
I do agree, though the idea of the electrically operated fuel pump being inside the tank used to disturb me, however, either through serendipity or design, I have yet to hear of a fuel tank fire caused by an electric pump. And when you think about it (and I realize that the current is limited to an extremely low value) the fuel gauge system is electrically operated, with a sending unit inside the tank that uses a contact that slides over a coil to make a variable resistor. And that type of setup has been in use since before I was born, let alone working on trucks.
Just as a possibly interesting story, I have been working in fleet and mobile equipment maintenance for about 29 years now. I've seen a few vehicles that caught on fire, some of them literally burning down to the frame & chassis. I've only seen one fuel tank that had combustion occur inside it without being damaged first. On this particular vehicle, a pickup cab & chassis, a tech was doing some welding in preparation of installing a utility body on the chassis. I don't know exactly what happened, but there was a flashover of some kind that caused a brief detonation of some sort inside the tank. There was no external damage and no fire beyond the momentary "flash" inside the tank. The interesting part is, that the tank "balooned" somewhat as a result, but did not leak, and after the incident, it held about 3 more gallons than when it was new!
--
Make it as simple as possible, but no simpler.

Larry Wasserman - Baltimore Maryland - snipped-for-privacy@charm.net
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This was 1975 GM carbutated. The X bodies in 1980 became some of the first with fuel injection.
Even

Agreed, however there would surely be times that a cap would be left off and at least a few times air would enter.

IIRC the tank sending units had enclosed electrical for the float arm.

I was in the industry about 23 years and never saw a problem with tanks either. I am missing something some where. I know that our factory rep could not explaing how the fuel pump would not cause an explosion.
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On Fri, 19 Jan 2007 22:34:19 -0700, Leon wrote

Not for Ford at least. The float arm ran through a slot directly to the wiper arm and resistor winding.
-BR

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GM did and or does have the round float arm make a 90 degree turn and go straight into a small sealed up housing.
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snipped-for-privacy@fellspt.charm.net wrote:

I'm not sure what that last sentence means, but I suppose that it means that their is pressure in the tank under normal operating conditions. That is certainly true since at least the 1960's and before fuel injection was common. The fuel cap is made with a valve that prevents fumes from exiting the tank but allows air to enter. This type of cap prevents the tank from collapsing and also results in water in the tank from cooling and condensation of moisture from the air that enters.
I haven't a clue about the electrical operation of the in tank pump. But even with a supposedly empty tank (engine stops running) thee will be enough gasoline to create a mixture of gasoline and oxygen that is too rich to burn.
Before any one starts arguing, I and everyone know that explosions and fires do occur around gas tanks. But those occur when a tank ruptures, a spark or open fire is at the mouth of the filling hole, or a very small amount of gas is in the tank when it is welded; all of those can provide at least a pocket of gas/oxygen mixture that will burn.
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Too rich to burn is real, but with all the possibilities...tough to figure.
Do know that fuelling accidents involving vapor pressure in gas tanks are the reason we have to have diesel ambulances now. Can't use the "200 treatment" phrase any more- 100% oxygen 100 mph- because they just never can get there. Used to be a bennie on a rural run.
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Leon wrote:

The mixture of gasoline fumes and oxygen would be too rich to explode even if the car ran out of gasoline.

No, just basic chemistry.

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So the car sits with the cap off for a week or two and someone gets in to start the car.
There is more to it than a hopefully too rich mixture. Out of millions of cars with this set up there are going to be a many chances offer the years for many of them to have the right mixture.
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snipped-for-privacy@swbell.net says...

You know, this just cries out, "Mythbusters"
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Have to ask them, I was just taking this:
Product Description From the Manufacturer This is an electric hacksaw for cutting pipe and profile steel when a spark free environment is required. The saw will cut pipes up to 24" in diameter and profile steel up to 21 3/4" height and 11 1/2" width. The saw blade needs 6 inches of clearance to make the cut. A pipe clamp is also recommended for cutting pipes.
off the website at Amazon at face value.
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They won't gift wrap it. That's gonna reduce its popularity as a present.
Prometheus wrote:

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(Amazon.com product link shortened)69086724/ref=sr_1_628/104-7821139-9460756?ie=UTF8&s=hi
I was shocked by the price tag for something that my recip. saw could do. And yes when is the last time you had a sawzall spark on you? Being that there is ventilation for the motor, one would have to assume that either it is made of some real high end materials (gold wiring, some advanced titanium, carbon fiber body) or that the price is in error. Also I would like to find the concrete and cast iron cutting blades for it.
I could see this as being spark free..
(Amazon.com product link shortened)69173627/ref=sr_1_153/104-7821139-9460756?ie=UTF8&s=hi
And sorry to our Canadian friends, it can only be shipped in the U.S.
Allen
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The last time I turned it on.
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Just the blade while cutting something. The mototr is a given.

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Cut through a nail with a bimetal blade while doing demolition. You often get a spark.
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wrote:

Will your recip saw take a 37 inch blade for cutting over 20 inches of structural steel?
As for the concrete and cast iron blades, it took me about 30 seconds of searching to find sources--google "fein hacksaw blades" and you'll get a link to the part numbers, google the part numbers and you'll get links to suppliers. The short (20 inch) concrete blade is over 70 bucks.
And there's no indication on the Fein site that either saw is "spark free".
The price appears to be because this is a honking big saw whose small blades are about the same size as the biggest blades for a Sawzall, and it's not intended to cut steel once in a while, it's intended to cut it all dfay every day.
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