It turned out to be a cracked diaphragm inside the fuel pump. This is what happened: I removed the fuel line from carburetor, crank it, no fuel. Removed the fuel pump, and put my finger over the pulsing tube and crank it, I can feel that pulsing suction so that's normal. I tried to suck that...
I've already cranked the engine a dozen times, it's just that fuel pump not disconnected yet. There's absolutely no fuel going through the filter -- it's bone dry (refer to picture).
Is it safe to say that pump not working? Or do I HAVE TO disconnect it then test again? To disconnect is just...
Fuel filter is in before the fuel pump -- judging by the fact that fuel filter is pretty dry (when it works there should be half cup of fuels inside that filter any time), I think it's safe to say that the fuel pump is either clogged or broken...
Thanks for the reminder -- just realized that this Toro 75742 does use a pulse-style mechanical fuel pump instead of a simple siphon tube. So if any debris yes that will be more likely to get clogged than the carburetor.
Guess that's what I'll do over the weekend. Taking out the carb bowl requires a complete disassembly, that's big job for me.
Really hope there could be some quick and easy way to get it back to work ... //sigh
Battery fully charged, sprayed a few puff of carburetor cleaner into the air intake, it will start, but stopped very quickly again, which means spark plugs probably are OK.
Strangely there was some fresh fuel leakage at the input side of the fuel filter. Checked the connector and clamps, both...