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  1. #1
    Join Date
    Jul 2010
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    Default electric wires in gas tank?

    Hey guys, I dont want to sound like a dumb ass but can someone explain how a electric fuel pump works in a gas tank. It does not make sense to me how this can be safe. I thought SPARK+FUEL=BOOOOM

    Thanks



  2. #2
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    Default

    Spark+fuel+oxygen=boom
    Greg
    1970 challenger convert-in process
    1970 barracuda-driver

  3. #3
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    Quote Originally Posted by gkring View Post
    Spark+fuel+oxygen=boom
    Exactly and in a gas tank you have fuel-spark-oxygen=no boom. Even with fuel+spark you'd still need oxygen to go boom.
    Andrew
    1987 Olds Cutlass Supreme FE3X Clone
    EFI455/T56/9" w/ 4.30 gears


  4. #4
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    But there is fuel and oxygen, but no spark. Think brushless DC and a fully encapsulated motor.
    VaporWorx. We Give You Gas http://www.vaporworx.com
    Carl Casanova's 1968 Camaro

  5. #5
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    Gasoline also has very high resistance.

  6. #6
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    Quote Originally Posted by BigBlockOlds View Post
    Exactly and in a gas tank you have fuel-spark-oxygen=no boom. Even with fuel+spark you'd still need oxygen to go boom.
    so dont run out of gas or your fuel tank will explode. jk

  7. #7
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    Quote Originally Posted by edog1 View Post
    so dont run out of gas or your fuel tank will explode. jk
    LOL---Manual pump anyone?

  8. #8
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    Oct 2002
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    Thats one of those things that no matter what, it just never will sit well with me... Pump is out of the tank on my car
    James J.

  9. #9
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    If it is so dangerous, Why are there pumps inside OEM tanks.
    Oliver Shultz
    It's OK to giggle and snicker. don't laugh and point

  10. #10
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    Because it's the best place to put it. The pump is submerged in fuel to keep it cool, the noise is masked by the pump, it takes up less roo, uses fewer hoses, etc.

    Also, OE's do not use just pumps in the tank. They use modules, which include many features that make them significantly better than just a pump.
    VaporWorx. We Give You Gas http://www.vaporworx.com
    Carl Casanova's 1968 Camaro

  11. #11
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    Jan 2011
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    Take an old pump apart sometime, you'll be surprised to learn that the fuel actually passes through the pump motor for cooling. There is no danger, as mentioned above, not only is oxygen necessary to support combustion, but there needs to be close to 14.7 times more oxygen than fuel by volume for ignition to occur. This will never happen inside a tank, not even an empty tank because the gasoline fumes will displace almost all of the oxygen. Think about it, other than in a collision, how many fuel tank explosions have you heard of?

  12. #12
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    Its always baffled me also. Good question. And not just fuel pumps, but fuel level sending units. Heck, they are sometime not much more than a coil of wire that the pickup lead passes over as the fuel level drops. There is electrical current passing though the leads and over the coil. I would have to think there is some sparking going on with a strip of metal riding over a coil. And the coil is not always submerged in fuel.

    Heavy fuel vapors must be the key. No O2 in the tank then huh?

    But? Fuel tanks are not sealed. As you use up the fuel you introduce air into the tank. So it would seem like an empty 20 gallon tank would be a fuel and O2 rich environment no? Replaced 18 gallons of fuel with 18 gallons of air. Plenty of air in your mostly empty tanks.

    And Im not thinking so much about the fuel pump, cause it should always be under fuel, even if you run the tank down.

    But what about the fuel sender coil? Now its in a fuel and air (O2) environment. You would think NO WAY do you want a spark to happen. But sliding contacts over open coils CAN produce sparks.

    I dont get it. And the thing is, they have been using open electrical components in fuel tanks forever (40 years in my case, maybe longer if my 62 had the same type of fuel level sender).

    What either ballsy or very smart guy decided that electrics in the fuel tank might be something to try out many years ago?

    Yup, Im very in tune with electricity and how it works, but to shove electrical components inside of a bomb, like a fuel tank is beyond my knowledge. That was a ballsy and tested theory back then.

    And so far I haven't seen any real positive explanations here. Some theory, like why it doesnt go BOOM. But no real explanations why. JR
    What I write is opinion, none of it is factual. 2010

    Even though I'm conscious it doesn't mean I'm coherent. 2011

    I'm getting better with age. Best thing about old age is I don't know any better. 2012

  13. #13
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    All things grounded won't spark I believe is the key. Fuel tank systems are always grounded when on so it is constant and when it fails the current stops. I could be wrong on the exact reasoning but that's what I would think would keep tanks from being bombs in the eyes of engineers.

    We surely aren't insane about the reality of a spark and fuel going kablewey since it gets us down the road! It would seem reasonable to think that it could arc and in a full tank it is a no brainer on its ability to blow up but when it is empty it must be as rich as a full piston full of gas and it won't blow.
    May The Horsepower Be With You !!!

  14. #14
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    Its kinda the same reason why a "flooded" engine will not fire.
    Mike Lara

  15. #15
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    It would seem reasonable to think that it could arc and in a full tank it is a no brainer on its ability to blow up but when it is empty it must be as rich as a full piston full of gas and it won't blow.
    i may be reading it wrong, but the way im reading it you have it backwards. a tank full of gas is way above its UEL and wont explode, a tank thats empty is closer to its flammable range, but still most likely above its UEL.
    Tim

    The WidowMaker: Garage Built 70 Chevelle

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  16. #16
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    Ok.............. the next time your at 30k feet on an airliner, think about the fuel boost pumps 2 per tank ( 3 phase 115v ). I have seen burnt pins on the pump cannon plugs, they are enclosed in a sealed Aeroquip hose assy, but sh*t can happen.

    One reason why I like first class and booze.
    Matt


    Current project: " Chain Reaction "

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  17. #17
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    Ok.............. the next time your at 30k feet on an airliner, think about the fuel boost pumps 2 per tank ( 3 phase 115v ). I have seen burnt pins on the pump cannon plugs, they are enclosed in a sealed Aeroquip hose assy, but sh*t can happen.

    One reason why I like first class and booze.
    uh oh, does twa 800 ring any bells? while boozing repeat after me; it was a missle, it was a missle, it was a missle..........
    Tim

    The WidowMaker: Garage Built 70 Chevelle

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  18. #18
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    My friend, a coworker, and my boss always run their cars down to empty before refilling. It was mentioned that the pumps are in the gas to keep them cool. Well, in the ast year, all 3 of their fuel pumps in their cars went out. When they went to replace them, the pumps in all 3 had gotten so hot that a wire melted off the pump inside the tank and was just hanging in there and no boom. So apparently its safe, at least with the pumps the OEMs use. It was a Ford, GM, and Jeep, and the same exact thing happened to all 3.

  19. #19
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    Don't most people run their cars to E before refilling? Out of everyone I know, I only know one person who doesn't
    Lots of autocross & track day videos of my car: http://www.youtube.com/user/TheDude023

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  20. #20
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    most modern tanks will have enough fluid in it to keep the pump cool.
    electrical systems in questioned are designed for submerged usage. Grounding circuits, low amperage circuits keep everything safe. I've seen a few pumps burst into flames when guys try to bench test them. Straight battery hook up with no fuse or relay protection.
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