blowing fuse :B:

[tom r]

I have a 1990 300sl Canadian edition. Fuse B keeps blowing ,this only happens after the engine starts but the engine runs fine.Would not be too concerned but feel this has something to do with the air injection pump and I have to get the Otario Etest done and ofcourse keeping the enviroment clean.I disconnected the pump clutch and the fuse still blew.Would like to know what all this fuse supplies.tks