Coffee Maker Cup Filling Process Not Working

Photo of a cat in an empty keurig box




My K40 Keurig coffee maker is having a problem filling the cup on demand. Only fills about every 10th attempt. Would you have any advice or tips on how to fix this problem? Thanks, Shirley.


Similar to what we just wrote about in response to an email from William and his K40, the problem Shirley describes is partial cup brewing and mostly like the result of an air pump that is under strain.

The role of the air pump in a Keurig is to build air pressure inside the boiler unit. It does this after the boiler unit has heated the correct amount of water to the correct temperature. The air pump them activates and forces this water out of the boiler unit, through the top assembly and entry needle, and into the K Cup sitting in the portion pack holder. This pressure then forces the coffee into your coffee cup.

Photo of the entry tubing being placed back on the boiler unit

When the brewer starts to produce a partial cup of coffee the normal cause is the air pump not being able to generate the correct air pressure. This can be the result of corrosion or other deposit build-up in the pump assembly. The corrosion or deposits are normally the result of moisture damage, with the leading culprit being a leaking solenoid that sits right next to the air pump (in the photo below the solenoid is the blue cylinder on the left, and the air pump the silver cylinder on the right).

Photo of the air pump wires feed through and free

Solution – The “Keurig Burp”

There are two solutions to try, the first being the “Keurig Burp”. This provides a short jolt to the area around the air pump that might help to dislodge deposit build-up and so free the pump and enable it to produce the correct air pressure again.

Our guide will take you through the simple steps to “encourage” the pump back into action.

A photo of the keurig burp on a K550 brewer

Solution – Air Pump Replacement

If the burp has not done the correct “encouragement” it may mean the pump damage is electrical or greater than a jolt can dislodge. And the best solution, and more permanent, is to replace the pump with a new one.

Our pump replacement guide shows you how to do this, with photos and descriptions for each step. For around $10 and some effort and time, this repair should get the brewer back to making full cups of coffee.

As we mentioned in our response to William, we encourage people to have a go if the machine is out of warranty and there are no other options. We recently wrote about Terri and her work to get her B70, a $225 brewer, back working for a total of $35 in parts. A K40 costs around $110, so $10 is a cheap option compared to buying a new one.

Photo of a Keurig B40 coffee machine

PS. We know the feature photo doesn’t have anything to do with partial cup brewing … but we thought it was cute; we love cats!