I have a 1988 22RE pickup. My problem is that the hot wire that is coming into the fuse box for the EFI relay is getting hot and melting the fuse. I have run a direct wire from the battery into the fuse box but it still heats the fuse and the relay up. So I think it might be the mass air flow sensor, but I'm not sure. Anybody got any ideas?

 

That will be hard to do on the PC.I would start by looking for bad (corroded) connections and tightening others.Got any added wiring;fans,amp,stereo,lights,ect.They need not be on that circuit.As far as a bad MAF, I doubt it.Relays that work make heat,but fuses should not.