to test the coil of the pump
put the meter on the diode setting
one reading will be open
reverse the probes (of the meter) and it will read value
same in ohm setting one side will read open other will read a value

Hello! I got a questions just on "Repairing a ULKA vibratory pump". I couldn't find an answer to it though those great picture, animations and schematics posted here are great.
So:
My standard Ulka pump from Lelit PL041 produce only 8 Bar pressure with blind basket. I got two such a machines, the second one makes 15 or so. What can bу wrong with my pump and how can I repair it? I've tightened the OVP up of course so it's not it.

Thank you. Picture attached

trololo wrote:My standard Ulka pump from Lelit PL041 produce only 8 Bar pressure with blind basket.

How did you test the pressure? It could be that the pump is fine and the pressure relief valve needs adjusting, cleaning, or replacement.

Well, the correction: I was probably wrong. The point is that another pump in my "reference" machine is 54W while this one is 48 (different letter indexes). It pump the water slowly, but makes those 12 or more Bars.
Not sure now, if I just need 9 Bar for proper brewing or 9bar and pumped promptly

Randy G. Thanks for helping!

Randy G. wrote:Just disconnect it and put an ohm meter across the feed wires to the pump, +/- and then -/+ and you can easily verify that.

The meter must have a diode junction capability. Some meters don't have enough voltage to forward bias a diode and will read the same on either polarity.

If the diode is blown both polarities will be open.
If the diode is shorted, both polarity readings will be the same.

So, I had the brew pressure inconsistency and pump going quiet problem that some of you had been experiencing. On the blank portafilter, the machine would pull at 9 bar and the pump would go quiet, and stall. On an actual shot, the pump would go quiet and drop down to 7-8 bar and run every second or so: "brum brum brum brum" would be the best way to describe it.

The previous 2 year old Ulka pump had just been replaced about 3 months ago because of a broken spring (the largest one in the assembly), and the new one had been sporadic in the last month or so. To try to resolve the problem, I descaled the machine and disassembled the pump, and found no issues. Still was having issues after that, then I found out about the check valve.

I pulled it off the machine, disassembled it, and made sure everything was fine. Might have been scale buildup around the ball, so I descaled it. Reassembled it and now the machine works perfectly.

So, for those of you with pump issues - check the check valve!

Spoke too soon, it's acting up again.

Guess I will order the check valve from Chris now.

What check valve are you referring to? Maybe the pump priming valve? That is capable of some disassembly - be careful - very small parts.



I believe if you "added up" all the solutions to this problem, a replacment pump would be the winner BUT, UNFORTUNATELY, that is not always the case. If you end up replacing the pump, go for new pump mounts while you're at it.

The pump priming valve that is on the left of the pump assembly. I removed it and cleared it out, put it back into the machine, and it was working fine for a day.

That is, a day until it started acting up again. The pump is brand new and I've already disassembled it to check for anything amiss - nothing there. I'm not getting much water flow out of the priming valve when the pump stalls either.