ACS Vesuvius pulsing pump problem-Please Help!

Pls

Hi everyone,
I’m at my wit’s end with a persistent pulsing water pump issue on my ACS Evo Leva V-1 and really need the community’s expertise.
Here is the full history so far:
The pump pulses irregularly instead of delivering smooth, consistent flow.
I have completed four full descaling cycles. After each one, the pulsing disappears midway through flushing — but returns the next day.
Following this pattern, ACS themselves recommended to change a (faulty non-return valve).
I replaced the non-return valve as advised.
However, replacing the valve hasn’t resolved it in my case, which suggests something else may also be at play.

I had presurestat failure before, ACS promptly sent a replacement and machine was back to normal.
Has anyone experienced this exact sequence — descaling providing temporary relief, non-return valve replacement not solving it — and found the actual root cause?

Any diagnostic steps or component replacements that finally fixed it would be enormously appreciated.
Thanks so much,

Pls.

Adrianmsmith

Pls Following this pattern, ACS themselves recommended to change a (faulty non-return valve).
I replaced the non-return valve as advised.

Faulty non Return valve usually causes pulsing whilst at rest and during pre infusion was rhis the case?

Adrianmsmith

A video would help to suggest something.
Long enough to see what’s happening not just a couple of seconds…..

Can you confirm tou have not been adjusting the pressure and hysteresis 🙏🏼 adjustment screws

Does it pulse at all when not in use or only whilst brewing or pre infusing.

Pls

Pulsing happens when you operate machine brewing, pre infusion or flushing water.

Have not touched any adjustment screws.

Will try to upload the video tomorrow.

Thank you

Adrianmsmith

Pls if that’s the case id suggest the pre infusion screw set point is set too low and does need adjusting. Not the hysteresis screw.

Pls

Adrianmsmith

Please do the same with a blind filter or fine grind coffee puck

Pls

Sorry, can’t find blind filter.

Done with single filter, double dose, very tight tamping.

Pls

Worked out how to do unlisted video 😄

Adrianmsmith

Video a normal double shot puck
Leave lever down at least 20 seconds

Video it all from this viewpoint please

Start video prior to pulling the lever down

Pls

Adrianmsmith

Thanks. I’m at a bit of a loss what this is.
Think my first move would he to adjust the pressurestat up to rule out a pump flow issue.
Best to use a blind filter.
If you do not have one, then make one by simply sticking some electrician’s tape in the bottom of the basket temporarily leaving just one or two holes for the pressure to reduce slowly when you are finished.
This is actually a better method than a true blind filter with the Evo 1

Do not go turning the screw Many turns plus or minus direction are indicated on top of the pressure stat.
Turn it very slowly and usually no more than a full turn and see if you can get to just under two bars without the pulsing.
Do not play with the smaller screw. That is for the hysterisis adjustment as this is normally set perfect from the factory.

@Cuprajake do you maybe have any other ideas?

Cuprajake

its not building pressure, pumps not working as it should, should be rapid fill.

has this just started?

there was someone else with this issue if i recall, but not sure what the results was

Adrianmsmith

Cuprajake
Its not but why the pulsing which seems to be an off/on of the pump but without pressure.
That’s why im thinking but may be missing the point is rhe pressurestat set very low.

Strange one without being able to touch it!!

I assume the water inlet hose isn’t blocked and is in the very bottom of the tank also?

Pls

ACS suggested that non return valve was the problem.

I have descaled machine few times and normal pump operation returned somewhere at middle (7litres) of flushing with fresh water.

Pulsing returned next day.

On one of the last flushes I have removed (disconnected) steam tank level probe cable, after disconnecting cable it triggered normal pump operation.

But later I cannot replicate the same operation.

I have ordered steam tank level probe and replaced it without further success solving issue.

ACS advised that non return valve wasn’t cleaned enough, so has been changed.

The issue not resolved.

Adjusted pressure to 2 bars now, have to wait till the morning for pressure to drop to much electrical tape used 😄

Thank you very much

Cuprajake

has it had a new pressure stat?

Pls

Yes, new pressure stat fitted.

Adrianmsmith

Pls Yes, new pressure stat fitted.

Did acs supply it or what model is it

Adrianmsmith

And you definitely fitted the non return valve in the correct orientation / direction ?

Adrianmsmith

Thats all i meant about ekectric tape