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Thread: check-valve in fuel system?

  1. #1
    Registered User AxtellZ's Avatar
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    Question check-valve in fuel system?

    Hi everyone-
    Can anyone tell me if there is or should be some type of valve to prevent fuel from draining back to the tank when the car sits? It seems that since last fall, when i put 72 SU's on my 260 & replaced the mechanical fuel pump (it leaked), when the car sits for any extended time (like overnight)- my fuel flows back to the tank. So I must crank the engine quite a bit to pump gas back up into the engine compartment before it will start (or so it seems).

    When the car has run recently, it fires immediately. I have noticed when i am under the hood at times, i can hear some sort of noise from the mech fuel pump area, like there is vacuum from the fuel flowing backwards. Perhaps my electric pump is faulty?
    Any ideas out there? It's not major, but an annoyance, and probably wearing my starter prematurely
    Thanks, Jeremiah
    Jeremiah Axtell, R.Ph
    Nunda, NY 73- 240Z, 74 -260Z

  2. #2
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    There should be some type of check valve but am not sure if it is in the fuel damper or if it is separate from it. The fuel damper is on top of the electric fuel pump, it's purpose is to even out the pulses from the fuel pump to avoid high/low pressure spikes in the fuel rail. Since I no longer have my 75 service manual I can't say for sure where it is but am pretty sure there is a check valve back there somewhere.

    Have you tried it without the mechanical pump in place? Actually, it's not needed with the electric pump. Might not hurt to try it sometime just to see what it does.

    It is possible your electric pump is not working at 100% and is not pumping at the needed psi. Got another one you could try?

  3. #3
    Registered User AxtellZ's Avatar
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    I don't have one (yet), but one of these days i am going to tear apart the fuel system. Get my gauge to read again, and sort out this pump, check filters, etc,etc Thanks!
    Jeremiah Axtell, R.Ph
    Nunda, NY 73- 240Z, 74 -260Z

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