Fuel pump assembly is leaking at the fuel return inlet. What to do? What to do? What to do?
After much consideration, decided to use epoxy compound to patch up the leak, because it is known to make a strong bond that becomes very hard. The first attempt didn't work, which could be because a regular 5 minute clear epoxy compound was used and the bonding surface on the plastic was not prepared properly. The most likely culprit is the fact that the fuel line is still pressurised, therefore fuel was weeping out from the hairline crack and prevented the epoxy compound from sticking to the plastic.
So, the return fuel line was disconnected, which resulted in some fuel spilling out. Fortunately a rag came in handy to soak it all up and any remaining fuel just vaporised under the hot sun. Then the plastic bonding surface and crack was carefully sanded with sand paper, followed by rubbing with tissue paper to remove the plastic dust. Finally a 3-ton metal epoxy compound was mixed and applied to the crack and surrounding plastic. The epoxy was left to cure for 24 hours, after which it became rock solid.
Reconnected the fuel line and ran the engine on idle for 10 minutes. No leaks were observed, which is good. Drove the car for another 30 minutes. No leaks observed too. So the epoxy compound patch works and I hope it will last long. Buying a new fuel pump assembly will cost US$ 250, while the epoxy just costs US$ 3.