Look at this picture of the fuse panel and notice the blue arrows. They point to the pink 20 gauge wire from the cluster feed fuse to the no.3 on the cluster plug
which goes to the fuel gauge.
The fuel terminal shown by the other blue arrow has a tan wire from there to the no. 4 terminal on the cluster plug which goes to the fuel gauge also.
here's a different view of the fuse box with the fuel terminal on the other end.
If you don't have these two wires you will have to run them to the cluster plug.
Just for clarity, do you have the gauge cluster or the light cluster with the charging light. It makes a difference because the pink wire goes to the no. 7 terminal on the cluster plug on the light cluster.