Electrolysis rust removal is easy but takes a some time.
-one 12v battery charger
-strip of mild steel
Step 1: Preparing the tank
Don,t worry about washing it out just shake out any loose bits if you can.
we will doing the tank in two parts, with the tank in its normal position and then upside down. both are done exactly the same way.
This instructable will show the upside down part, but right side up is the same method.
Do this in a well ventilated area, prefably outside as the process of electrolysis will produce hydrogen gas!!
Make sure the tank is stable and block any pipes coming out to prevent leaking.
Make sure the cap seals properly, if in dought use some plastic to help it
Remove the fuel level sender