Betcha the air pumps purchased are aftermarket as they have a tendency to be quite noisy( ie Doorman, NAPA-which is ,made by Doorman, here anyways). ACDelco are quiet right out of the box but.....................double or more the $! Jerry

 

It is a 1999 model. After we put the pump in we reset the codes. They have not come back on, but I the noise just sounds like my blazer should be on a runway..

 

Yes it is a Doorman, as a matter of fact. I will look into a acdelco model. So I am guessing the noise never goes away? If I buy an acdelco, it will make the 3rd time we have replaced the smog pump.

 

I just went through this nightmare trying to pass emisions. Check the pump, if it is running and I see from you post it is, then the 30 amp fuse and relay are good. Mine was blown and the pump was toasted. So I bought a new fuse and pump. little did I know that there is a selinoid next to the air pump that is run by a 10 amp fuse next to the 30 amp fuse in the fender. Make sure the 10 amp fuse is good. If so check the selinoid attached to the vacum hose from the engine and vacum hose to the check valve to see if it is opening when the pump is on and closing when the pump goes off. Mine wasn't, the selinoid was stock closed. Next pull the check valve attached to the pump hose and other vacum hose, it should be open when pump is on and closed when pump/selinoid is off. Mine was stuck closed aslo. I started mine up with the selinoid and the check valve in hanging and made sure the valve was open and the working when pump was running and then closed when the pump went off. Light is off 2 weeks now. i'm fighting with my coolent temp now.....

 

Sure did. It was fine.

 

jumping in late to mention. I replaced mine with an aftermarket and it was loud to the day it stopped a few months after. I pulled the plastic housing to find the fan was striking against the inner plastic cover. I went through the 'free the armature from rust project", repositioned the gasket and tightened it less and same noise. I installed an AC Delco and I thought it was bad out of the box until I saw the engine light went off on the third or so trip and I then realized it was quietly working.