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Q: Hunting idle speed and stalling.

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2003 Honda Civic ES (7th Gen). Used car 2 days before and everything was fine. When I drove it now, it has hunting idle. Saw gas empty on dash although I know it has quarter tank full. Filled up full tank on gas station, and when I tried to start the car, it wont start. Sounds like a bad battery... Pushed start car and it started fine but gas gauge still reads empty though it should be full tank. I cleaned the throttle body and Idle Air Control Valve. Car is fine now. My Question is, what caused my car not to start and read empty fuel although it has full tank? And why it didn't want to start? Car is fine now which reads full tank and runs fine but idle is still 1,300 rpm. Did idle relearn, still wont fix it. I can live with the rpm thing but I don't want to experience the no start thing. Checked battery and Alternator and both are in tip top condition. Everything is fine now but i want to prevent it from happening in the future. Hope you can help. Thanks in advance and God Bless.

My car has 120208 miles.
My car has a manual transmission.

Hi There, It sounds like you may have an issue with your evaporative emissions control system causing the hunting idle problem and the no start issue after filling up your fuel tank. Your car has a small purge valve called a purge solenoid that controls the venting of fumes from the fuel tank as these fumes build up inside, particularly when you are refueling the car with gas. The EVAP system prevents fuel vapors from the fuel tank from escaping into the atmosphere. The EVAP system collects and temporarily stores the fuel vapors in the charcoal canister. The charcoal canister is filled with activated carbon pellets that can absorb the fuel vapors. When the engine is running, the fuel vapors are purged from the canister and burned in the engine. The vent control valve (solenoid) controls the flow of outside air in and out of the charcoal canister. The vent valve is controlled by the engine computer (PCM). Normally the vent valve is open. It closes when the engine computer tests the EVAP system for leaks. If a leak in the EVAP system is detected, the Check Engine light will illuminate on the dash and the trouble code related to the problem will be stored in the engine computer. When an air leak is present in the EVAP system, the MAP sensor will not be able to determine the air density, and the MAF sensor will not be able to determine the volume of air, entering the engine correctly. This will lead to an over fueling situation or an under fueling situation depending on the size of the air leak and engine operating speeds and load. This may eventually lead to catalytic converter problems as well as misfiring problems. I would recommend having an expert from Your Mechanic come to your location to diagnose and inspect your vehicle.

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