cheap electric pump - no adjustment?

[AndyJ]

I wanted to upgrade from my old 2" tube and Mityvac and ordered one of the cheap electric pumps online. 2-1/2" tube and electric pump on a pendant for $30. It arrived promptly and works, but the instruction booklet doesn't mention anything about setting the vacuum. Push the "on" button a couple of times and it pumps while the digital readout climbs to 350, then it shuts off and it drops down to 300, then back up to 350, etc. No indication anywhere of what "350" is, but I'm guessing mm Hg. 350 would be 13.8" Hg; *way* more than I want.

If I just press the "on" button once the pressure climbs until I let go, at which point it just slides down to zero.

Does anyone else have one of these things who can give me some pointers on how to operate it? Or is it really just hardwired to 13.8" only?

I know I can message the seller, but I figured I'd ask here before opening Door #2...

[bucket]

I had one of these a while back, it's a Hercules pump. It worked pretty well but then I had a problem with it for some reason and it wouldn't pump. If I recall you set the pressure by starting it up then pressing the second button when you reach the pressure required. It then cycles to maintain the setting. It worked pretty well for a little cheap thing like that.

[AndyJ]

I thought I tried that, but maybe I didn't press the button for the right amount of time.

Thanks bucket, I'll give it another try!