If you haven't found something already, i found a place online where you can buy a plastic fuel pump cover, as well as many other parts for this particular outboard. Here is the website
http://www.marinepartsplus.com/catal...5/+52325/444-8
The part you need is is number 7 on the list. I had this same problem and tried JB weld to seal the crack, this worked to start it, but as soon as a put it in gear and increased the throttle, it would stall and i would have to decrease it again to keep it running. I ordered a new cover and i hope it will solve my problem. Best of Luck!!!