Hi, Anonymous you need to locate the fuel flow origin first to isolate the problem area otherwise the usual suspects are:
1. Fuel tank empty.
2. Fuel cap or fuel tank not venting properly.
3. Fuel filter clogged with rust or dirt.
4. Vacuum line to fuel valve clogged, cracked, pinched, bent, broken, or missing*
5. Faulty vacuum line switch/relay
6. Petcock clogged or diaphragm cracked, cut or torn*
6. Fuel line from the fuel valve/petcock to the carburetor clogged, cracked, pinched, bent, broken, or missing.
7. Vacuum lines to the mechanical fuel pump clogged, cracked, pinched, bent, broken or missing.
8. Faulty electric fuel pump and or wiring.
9. Fuel line from the fuel pump to the carburetor clogged, cracked, pinched, bent, broken, or missing.
10. Carburetor inlet fitting clogged.
11. Carburetor float and or needle and seat stuck.
12. Carburetor overflow line clogged, pinched, or bent.
13. Vacuum line from carburetor deacceleration valve not zipped tied.
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