I rebuilt the Throttle Body on my sons 1st Gen 89 S10 Blazer 4.3L. After trying to start it, fuel was leaking from where the fitting for the fuel line goes into the TB. Couldn’t find just the gaskets/seals I needed, so bought a whole new TB rebuild kit for 2 gaskets. Put those on and the damn thing still leaks! I’m at a dead end. Came real close to burning it today.

 

The fittings I believe are flare fittings. Remove the fuel line from the TBI and slide the fuel nut back down the line and inspect the flare at the end of the tube and inside the nut and I would also inspect the inside flare of the TBI. if there are any scratches or grooves in the flare connection points that could be the reason for a leak,

 

If the leak is at the TBI adapter and not at the fuel connection make sure that the adapter has the small seal at the tip of the adapter and I believe there is a seal for the body of the adapter to the TBI.

 

https://nemigaparts.com/cat_spares/e...03/gm03-145/Rt
The TBI adapter had a small seal at the tip and and the fuel line has an o-ring at the tube end. It has been a while since I had my TBI apart.