There seems to be a loud hummmmmmm comming from the trunk/gas tank area of my 88 5000q. I suspected it was the fuel pump and had it checked out by my local mechanic. He said that the pressure was ok,although I should get it replace as when they go i come to a dead stop. Given the high price for this item plus labor to put it in, would buying a used one from a junk yard make any sense?