How often and when should the air pump come on? I Is it audible? I dont hear anything from mine and it blew the fuse... 93 Z28 I installed a new fuse, still hear nothing??

 

It should only come on for a few minutes when the engine is first started to help the cats light up faster. Usually the fuse blows when the bearings in the pump or motor go bad or seize, causing the motor to draw excessive current.

 

Thank you for the input!!
Mine makes no sound whatsoever. Dont know if youve seen my posts about the idle issue Im having, but I noticed today when it dives down and wants to stall, there is a noticeable drag on the sound of the fuel pump....like you said it sounds like amp draw. I wonder if this has something to do with my issue... I got a new AC Delco pump for 140 bux shipped which alot less than any others on ebay. Heres to hoping!! Perhaps theres enough drag on the charging system to cause it to want to die every few minutes during cold start/idle operatopn????

 

When the engine rpm drops below a normal idle, the alternator will stop charging and the voltage in the system drops a couple volts. That is probably what you are hearing.

 

Could be, but, there is an amp draw being experienced, because its blowing the air pump fuse...

 

Two different issues. I was referring to the sound from the fuel pump.

 

I understand...heres my train of thought...

Air pump tries to kick on....

experiences an amp draw due to malfunction...

this drags on the charging system...causes issues with all the electrical sensors during cold idle operation, including the PCM all the way to the spark plugs.

just at that moment, the idle dives down...

as a result I can hear the whine of the fuel pump slow for a second or two.

This happens every few minutes during cold idle operation only. maybe the air pump trying to fire up is pulling everything down far enough to try n kill the engine. When warmed up, theres no problem at all.

My plan is to let it get back to room temperature overnight, put in a new fuse, keep the air pump unplugged, then see if it idles the same... Im trying everything I can....Im really out of ideas otherwise. Ive replaced every damn sensor in the system.!!!!!!!!!!

 

The A.I.R. pump runs only a maximum of 4 minutes (240s) after the engine is started cold, shorter time when warmed up until the engine goes into closed loop operation. A simple relay, driven by the pcm, controls the power to the pump. After the 4 minutes, the pump never runs again until a restart. You statement of "This happens every few minutes ..." should not apply to the A.I.R. pump operation. You can verify this however by simply removing the fuse that blows.

 

The problem I encounter when removing the fuse is a code 26 sets within a few minutes. I timed when the engine took its first dive a couple days ago...dont know why, but it was right at 4 minutes! I dunno! Your input is appreciated. Im gonna get this damn thing fixed yet!

 

Instead of removing the fuse, which may or may not be affecting other components, unplug the air pump. I rather doubt the air pump draw is causing your other problems, but might as well take it out of the equation.