* Fuel Pump: The most probable cause. Pouring gas down the carb temporarily bypasses the fuel pump. The pump might be weak, failing, or have a clogged fuel filter. The clicking is likely the starter solenoid engaging, but the engine isn't turning over because it's starved for fuel.
* Fuel Filter: A clogged fuel filter will restrict fuel flow, leading to the same problem. It's a cheap and easy part to replace, so it's worth checking first.
* Fuel Pressure Regulator: This component regulates the fuel pressure in the system. If it's failing, it could be causing inconsistent fuel delivery.
* Carburetor Issues (Beyond Initial Flooding): While pouring gas in got it running, there might be other carburetor problems. A sticking float, clogged jets, or a faulty accelerator pump could prevent fuel from reaching the engine consistently after the initial "shot" of gas.
* Battery/Wiring: Though you tested the starter, a weak battery or a corroded connection somewhere in the starting circuit could still be contributing. Make sure the battery terminals are clean and tight. A voltage drop test across the battery terminals while cranking will reveal if the battery or wiring is the problem.
Troubleshooting Steps:
1. Check the fuel filter: Replace it. It's the easiest and cheapest fix.
2. Check the fuel pump: Listen carefully for the fuel pump whirring when you turn the ignition key to the "on" position (before cranking). If you don't hear it, or it sounds weak, the fuel pump is suspect. You might need a fuel pressure gauge to test the pressure it's delivering.
3. Check fuel lines for leaks or blockages: Visually inspect the lines between the tank and the carburetor.
4. Inspect the carburetor: Look for anything obvious like a clogged fuel filter on the carb itself or a stuck float.
5. Battery and wiring: Clean terminals and check for loose connections. A voltage test while cranking will help determine if there's a voltage drop issue.
Important Note: Repeatedly pouring gas into the carburetor is a very temporary and potentially dangerous fix. You risk fire and damage to the engine. Diagnose and repair the underlying fuel delivery problem as quickly as possible.