Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Equus 3660 hand vacuum pump a real bummer!

Attempted brake bleeding with Equus pump. After carefully following factory instructions, the unit appeared to inject more air than it extracted. Checked bleeder screws for leaks around threads, but that did not appear to be source of the problem. I was successful in flushing out my brake system, but once finished brake pedal went straight to the floor. So, I'll start again tomorrow using the old method of having my wife push and hold the pedal while I crack the bleeders. Intend to request a refund.