Hi, Jinn_unlimit the first thing I would do is take it back to your mechanic since he was the last one to work on it and the usual suspects are:
1. Severely discharged or a damaged battery, should have 12.5 volts or better and be able to pass a "LOAD" test if necessary, your battery may show 12.5 volts but have little or zero amps and needs to be replaced.
2. Failed alternator/generator and or voltage regulator.
3. Loose or corroded battery terminals and or cables especially the "NEGATIVE" cable, look for loose, corroded, or broken connectors inside the cable harness at "BOTH" ends.
4. Failed main circuit breaker or ignition switch, check for loose connections and continuity.
5. Failed system and or ignition relay, check for continuity.
6. Failed ignition coil, stator, magneto, points/condenser ignition/electronic module.
7. Failed CKP, CPS, CMP, MAP, TPS, or BAS sensor, corroded, loose or broken wire connector pins/sockets.
8. Throttle cables and or idle speed improperly adjusted hot idle speed should be 950 RPM to 1000 RPM.
9. Air/fuel mixture screw improperly adjusted.
10. Accelerator pump damaged or not working.
11. Water or dirt in the fuel system, carburetor or filter.
12. Restricted, blocked or kinked fuel line.
13. Fuel tank empty.
14. Fuel tank contaminated with ethanol sludge.
15. The gas cap is not venting properly or fuel tank venting system blocked.
16. Vacuum line from intake manifold to petcock broken, cracked, or not attached, carburetor vent line plugged.
17. Needle and seat stuck closed in the float bowl.
For more information about your issue and valuable "FREE" downloads that you need please click on the blue links below. Good luck and have a wonderful day.
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