My 2000 Tahoe makes a sounds like an electric motor or some type of pump is running right after I start it. It does not always do it, but when it does it is very noticeable. Asked the dealership where I bought it and they said it was the fuel pump building pressure ( Quite normal). My concern is that it does not happen every time and if this is normal, souldn't it be consistant. Also it seems when I step on the gas peddle it stops. My brother has a 2001 Suburban, same engine, which is also the same engine as my 99 silverado 5.3 Liter, both do not make this sound. Should I be concerned????

only if its in warrenty, otherwise you might jinx yourself with a slap in the wallet.

Sounds like the A.I.R. Pump. Mine does the same thing.

Example, the first 15 seconds or so, the "motor" sounds really loud and then it stops?

I asked gm last time my tahoe was in, and thats what the guy told me.

Makes Sense.