Robert Bruffett

Hey js. So I replaced the o2 sensors on the passenger side. The brand is kax. The thread was melted on the output sensor but I got the other on somehow. Either way. Now on to the pump. I checked the pump. I took off the black rubber pipes and felt the wind first starting from the pump then took it to just before the valve. Felt it blowing a lot of air. It was humming pretty loud to from the air coming out. While it was on and the pump shut off I took my attention to check the valves and I can kinda feel air popping back when the pistons are firing or whatever makes it pop back there. Here's a couple of pics of the valves n stuff.

Thanks js I'll try those. I just got my other o2 sensors in. They are not those brands though. So I'll change them and check the pump and work my way from there this weekend

Please Im hoping anyone might have some advice. I have a 1999 chevy silverado 1500 with 5.3L. I am getting the code p1415. I got this code when it was on non-op 4years ago now I'm ready to fix. It popped up with o2 sensor codes in which I changed 2 so far. And now I'm back to the p1415 after changing both check valves and feeling air blow through the pump. Right now I'm a little lost on what I should do next