my 90 n/a keeps blowing the engine fuse,I thought maybe the fuel pump went bad so I changed it,checked the cas (because i was getting a code)changed the main relay,also the relay under the dash.any thing else I should look for?

 

On an S5 the 15 amp Engine fuse powers the Main relay, Circuit Opening relay, and an item related to automatic transmissions. You could go about this in different ways. You could disconnect the two wire plug to the Main relay which houses a Black/White wire, and disconnect the Circuit Opening relay as well and turn the key to on and wait for a while as much as 15 minutes or so and see if the fuse blows or not. If it does not then turn the key off briefly to plug in one of the two disconnected items then turn the key back to on and wait to see if the fuse blows or not. If it doesn't then the problematic item/wiring is related to the other item.

 

I replaced the main relay already,is that the only thing that the 15 amp fuse powers?I tried it now and I have spark but no fuel,when I pray starter fluid in the throttle it starts but blows the fuse.

 

Reread the post and focus on the first sentence!

 

I did as you said,and when I connected the circuit opening relay it blew the fuse,what do you think can cause this?

 

The Black/White wire (top row center position in the plug) at that relay which is supposed to have voltage w/key to on has a short in it.