I have a 91 hb with a 90 ls swap. It recently started throwing a code 43. I think it is fuel supply system. I have a turbo kit ready to go on but I am waiting to figure this problem out(better safe than sorry). I don't know exactly what could cause this code so any help would be great thanks.

 

I looked the code up and it says "left fuel supply system"

 

Any suggestions on what I could do to get rid of it?