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Thread: 6910 low pressure.

  1. #1
    Senior Member Jackster's Avatar
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    6910 low pressure.

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Stupid spare machine...
    It's been sitting out the shed, and it's a unknown machine to me. Thought I might go through it and get it up and running. So, descaled the steam and the brew paths (steam path with the element disconnected)
    Gave it some backflushing too, getting good suds out the drain into the tray.

    So, my issue... It won't build good pressure, most times it barely moves the pressure gauge! The gauge works, as I verified it with my portafilter gauge.
    Occasionally it makes pressure, but takes like nearly 1minute to build around 6bar.
    It's not passing pressure out the drain.
    It's not passing pressure out the bleed line on nose of pump.
    It's not a blocked 3way solonoid (as the gauge is before the solonoid.
    I have had the 1way valve in the pump nose apart, cleaned and then- no difference!
    Replaced pump with another (including 1way), no difference!
    Both pumps have good flow. Shower head removed...

    It's definately not building pressure, as the pump doesn't cycle. (Y'know, it does the bit quieter, bit louder cycling)

    Not leaking water out the bottom, or the hot tap, or the group seal (I know it's not recommended to be using a blind filter, but it will be ok if I don't run it all the way to 15bar)

    Stumped guys! Is there anything I have missed?

    I'm not putting any new bits into it, there is a few spares laying around here from another machine.

  2. #2
    Senior Member level3ninja's Avatar
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    Quote Originally Posted by Jackster View Post
    Both pumps have good flow. Shower head removed...

    It's definately not building pressure, as the pump doesn't cycle. (Y'know, it does the bit quieter, bit louder cycling)
    When you say both pumps have good flow, does that mean you ran them with the hoses running to / from a bucket or something to test them? I thought the "cycling" was the pump turning on and off to allow the water time to sit in the thermoblock and heat up.

    If you have a spare PCB I'd be trying that first.

    If you know a licenced electrician with a multimeter I'd get them to test the voltage at the pump. I'm away on holidays for another week and a half but I can test the machine I have at home once I get back if it would help.

  3. #3
    Senior Member Jackster's Avatar
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    Not cycling on and off, like cycling as in at full pressure.

    I have a patch power lead on it now, straight to the pump, and the pressure gauge directly on the top of the pump. Pump is fine for pressure, and rate of pressure is immediate.

    Back assembled in the piping and no pressure.

    Will flow the pump... And actually measure it. Can only think of a group head blockage.
    The gauge is after the group head, on the return, so it won't detect a blockage in the group.

  4. #4
    Senior Member Jackster's Avatar
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    https://youtu.be/CR8yxCSZ_v8
    This is my old 800es shot as a example of the pump cycling. It's still powered and pumping, but freewheeling because of the pressure.
    My simonelli does it now that I have set it's opv too.


    Cycling like this. From the 38-50sec mark.

  5. #5
    Senior Member Jackster's Avatar
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    Flow test. 550ml per minute out the top of the pump, 350ml/min at group head...

    Descaling again...

  6. #6
    Senior Member level3ninja's Avatar
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    Quote Originally Posted by Jackster View Post
    I have a patch power lead on it now, straight to the pump
    So the power to the pump is coming straight from the wall, not going through the machine? You need to do a flow test where the electrical supply to the pump is from the machine as normal but the plumbing had been rerouted to remove any possible plumbing issues. From what you're saying it sounds like the pump is not getting the right electrical supply.

  7. #7
    Senior Member Jackster's Avatar
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    Getting better... It's picking up pressure ok now, I left some descaled in it for a couple of days.

    It's putting the needle into the red pretty comfortably now with what looks to be a normal pressure rise time.

    It's got a dripping hot tap now, not many solutions for this around.so, have given the needle a light sand for a bit better seal, but it either is bottoming out, or the seat needs a clean up. Considering how to clean the seat up, I think I will glue a small bit of sand paper onto a spare needle, and cutting it's threads off so I can use it as a hand tool.
    Not sure, need to have a look...



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