Something's leaking

If you're having trouble pulling below 1000 microns, you're not alone. The solution to it might be easier than you think though.

First make sure that the pump is not the issue. Attach a micron gauge directly to the pump to make sure it can pull down to the desired microns.

Which core tool are you using? Some off-brand core tools' Schrader's will sit a bit low on the side port, and is sometimes not fully actuated by the core depressor in the coupler used to attach the BluVac.

The core depressor in the coupler is screw-in type. Turn the depressor 2 turns and try again. The partially open schrader does not allow proper gas pressure to be communicated to the sensor.