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Pretty simple question, if liquids are incompressible then how is fuel pressure "stored" when the fuel pump isn't running, i.e. after turning to run and waiting a few seconds, but not turning to start?

Edit: To clarify, I'm asking more what part of the system is compressed to provide the constant pressure, is it in fact the fuel, the lines expanding, something else?

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By the use of one way or non-return valves. Which is why most fuel systems have warnings about which components / pipes should be disconnected or not or the order when working on them - some are at very high pressure.

Also note that liquids are compressible, but as it needs a lot of pressure for a small volume change, us engineers assume incompressible as it simplifies some of the maths. Some systems have a pressure chamber or use the flexibilty in the pipes - it all depends on what parameters need to be covered.

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  • I guess what I was asking more is what part of the system is actually compressed to hold the pressure? Is it the small amount of compressing that the fuel is capable of, or the lines expanding, something else?
    – Ceshion
    Jul 7 '17 at 12:00
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    Ok , first thing liquids are compressible, but as it needs a lot of pressure for a small volume change, us engineers assume incompressible as it simplifies some of the maths. Some systems have a pressure chamber or use the flexibilty in the pipes - it all depends on what parameters need to be covered.
    – Solar Mike
    Jul 7 '17 at 12:05
  • That answers my question! If you wouldn't mind adding that to the answer, I'll accept it c:
    – Ceshion
    Jul 7 '17 at 12:16

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