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Technical Carter fuel pump won't switch off

Discussion in 'The Hokey Ass Message Board' started by blackjack, Jul 18, 2021.

  1. I've got a Carter fuel pump on my newly finished Pontiac powered 27T Modified. Nothing special, just a basic low pressure one for carbs.

    My problem is that it never stops pumping - even the carb bowls are full. I read that this is a feature of some Carter pumps.

    Is this true? Think I will be investing in an SU pump
  2. Mike VV
    Joined: Sep 28, 2010
    Posts: 2,581

    Mike VV
    from SoCal

    First...which pump ? Carter has many..! We (the readers) have no crystal ball.
    Second, NO...the "pump" does NOT turn off when the bowl'(s) are full. This can never happen, the pump will pump as long as the engine is running (mechanical), or the electrical switch is not turned off (electrical pump). Beside, the pump has no clue when the carburetor is full..!

    The carburetors needle and seat close off the fuel flow when full, or open when the bowl(s) need fuel.

    UNLESS...your pump is pushing too much pressure. That's the owner/builders problem..! YOU must figure out how much pressure the carburetor needs and have the regulator set to that value, or just under.
    Do you have a regulator plumbed into the system ? Sounds like you should.

  3. squirrel
    Joined: Sep 23, 2004
    Posts: 50,933


    There are basically two types of electric pumps: the pulse type, and the motor type. The motor type runs continuously, and has a pressure regulator (either in the pump or downstream from it) that limits pressure. The pulse type has a regulator built into the operation of the pump--once it builds enough pressure, it won't pulse until the pressure drops again.

    you have a motor type pump, so it runs continuously.
  4. Thanks. I've never used an American fuel pump before so wasn't sure. I think I will swap it out for an SU that just cuts in when the pressure drops. The Carter is noisy despite being rubber mounted.

  5. squirrel
    Joined: Sep 23, 2004
    Posts: 50,933


    Yes, the Carter pump is noisy. The motor type pumps can move more fuel than the pulse type, so they're more popular in cars that have bigger engines, etc.
    dirty old man likes this.
  6. JeffB2
    Joined: Dec 18, 2006
    Posts: 9,124

    from Phoenix,AZ

  7. It doesn't run when the ignition is off and it is separately switched anyway. Just runs all the time when the ignition is on and the fuel pump circuit is switched on but I now think that it's meant to and a relay doesn't stop that happening. It also runs through an inertia switch so it switches off in the event of an impact.
  8. sunbeam
    Joined: Oct 22, 2010
    Posts: 5,607


    I still run Stuart Warner 240a pumps kit them and go
  9. Truck64
    Joined: Oct 18, 2015
    Posts: 5,316

    from Ioway

    JeffB2 likes this.

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