Took a look again at Kidbenz a couple of minutes ago and it really sounds like a low hum instead of a hiss.
Sort of like a ship's horn.
Logically, it looks like a vacuum problem. By the way, the hissing sound near the fuse box has gone...hmmm...have to look for vacuum leaks i guess...
But the slight petrol odor near the right rear sight is still there.No visible petrol leaks.
I swapped his OVP relay (old single fuse type with black?? top) with my spare one (dual fuse with red top) and we'll see if it solves his starting problem. Haven't swapped out his Fuel Pump Relay with my spare one coz we wanna see how it goes with the OVP.