Here's a breakdown of the most likely culprits, ordered from most to least likely:
1. Fuel Pump: This is the prime suspect. The fuel pump is responsible for drawing fuel from the tank and delivering it to the carburetor. A failing fuel pump may not be able to provide enough pressure to keep the engine running consistently. It might work intermittently or only when gravity assists (like when you added gas directly).
2. Fuel Filter: A clogged fuel filter will restrict fuel flow, leading to similar symptoms. The filter can become clogged with debris or rust.
3. Carburetor Problems: While less likely given the immediate response to added fuel, there could be issues *within* the carburetor itself. This could include:
* Clogged jets: Small passages in the carburetor can become blocked, preventing proper fuel flow.
* Diaphragm issues: If the carburetor has a diaphragm (likely), a leak or tear can affect fuel metering.
* Float level: The float may be stuck or misadjusted, causing the carburetor to run either too lean (not enough fuel) or too rich (too much fuel).
4. Fuel Line Restrictions: A kink or blockage in the fuel line between the tank and the carburetor could restrict flow.
5. Ignition Coil (Less Likely): While less probable given the response to adding gas, a weak ignition coil could cause the engine to die after a few minutes if it's overheating. However, it wouldn't explain the immediate response to extra fuel.
Troubleshooting Steps:
1. Check the Fuel Pump: Listen carefully near the fuel tank while someone tries to crank the engine. You should hear a whirring sound from a working fuel pump. If you don't hear anything, or hear a very weak whir, the fuel pump is likely the problem. You can also check the fuel pressure if you have a gauge.
2. Inspect the Fuel Filter: Locate the fuel filter (usually a small canister on a fuel line) and check its condition. If it's visibly dirty or damaged, replace it.
3. Check the Fuel Lines: Visually inspect the fuel lines for any kinks, cracks, or blockages.
4. Carburetor Inspection (Advanced): This requires more mechanical skill. You'll need to examine the carburetor's jets and float level. If you're not comfortable with this, take it to a mechanic.
Safety First: Always work in a well-ventilated area when working with fuel. Never work near an open flame.
Recommendation: Start with the fuel pump and fuel filter. These are the easiest to check and are the most likely culprits given the symptoms. If those are okay, then move on to the fuel lines and finally the carburetor. If you're not comfortable working on the carburetor, take it to a qualified mechanic.
