I am going to assume from that part of your question that this is an older rig that you don't really want to pour a lot of money into, correct?
This stuff:
https://www.amazon.com/dp/B0000AXYZG/?tag=atomicindus08-20
My father used it to glue the toilet tank lid back together when I was about 4 years old. My mother sold the house when I was about 34 with the same repaired toilet.
We sold the stuff in our stores.
I was on the counter at the Yelm store one afternoon, and a guy drove into the parking lot and stopped right outside the front door with fuel dribbling out from under his car. Left the engine running.
He came in, pulled two packages of Seal-All off the rack, paid for them, and went out and ripped them both open and crawled under the car laying on his back.
He just started globbing the stuff onto the leak until it stopped, then opened the second tube and globbed on some more.
No prep, no sanding, no wire brush - just glopped the stuff right on over the dirt.
Best testimonial I can give you.
I use it to repair leaky fuel tanks on lawnmowers and those silly "Pulsa-Prime" carburetors that leak where the check ball is pressed into the side of the plastic main body of the carburetor.
Repaired area of tank is the top seam at lower right:
Briggs_10H902_Carburetor_04 by
four.cycle, on Flickr
Used it yesterday to glue the head back onto a little garden statue.
About $5 bucks at Ace Hardware.
Or.... go find another tank.
* let me add: I
always allow it to fully cure at least 24 hours before exposing it to gasoline. your mileage may vary. *