Battery Light Flickers At Idle

1989 Thunderbird 3.8 V6 Base Model

Ok, the battery light is flickering off and on when i'm at idle. while driving the battery light does not flicker or come on at all. i think its worth mentioning that not to long before the battery light begin to flicker i put about 10 gallons of gas in my tank. the gas station was pretty flooded due to heavy raining. after putting the gas in my tbird, it stalled out and i had to get my mechanic to start it. once he got it started he said the engine was running like it has water in the gas. he also said that particular gas station i went to is known for water getting into their tanks when it floods.

the reason im mentioning the water in the gas is because i think my tbird is idleing a little low. i dont have a tach. so i cant be sure. but i know my bird, and im sure the water in my tank is causing it to idle low, and i think that could be causing the alternator not to operate properly. any ideas? i dont think its the alternator, it sounds fine.

Best bet is to get a voltmeter and test the power going to the battery. A battery should be getting 13.5-14 volts from the alternator. If the idle is low more likely then not the alternator is not able to produce enough current.
So test the battery with the voltmeter at idle then have someone rev the engine and test it again that will tell you if low idle is causing the problems you have.

Too much water in the fuel system can cause pistons and valves to burn. Don't ever go back to that gas station again.

i put a couple bottles of water remover in the tank and also a bottle of sea foam. its running much better now, but you can believe that will be the last time i ever get gas from that station. to add insult to injury, it was an exxon station. you would think with all the record profits exxon mobile is making, they could find a way to keep gas in their tanks, and keep water out.

as far as the battery light situation. i havent had a chance to test the voltage yet, but after driving all day today, it wouldnt start. i put a battery booster on it, and it started up. after removing the booster the car did not stall or anything, but the little fluid level indicators begin to flicker off any on, and the radio (aftermarket) begin to flicker off and on too. but it continued to run. right now i cant get it started because the booster needs to be charged. im thinking the battery is really weak. its only 2 years old, and its an interstate. but i did have overheating and head gasket problems not to long ago. could that heat have caused the battery or alternator to fail?

but i did have overheating and head gasket problems not to long ago. could that heat have caused the battery or alternator to fail?

Not exaclty sure if thats the cause, but i sure dosent help.... Head gasket is a common problem w/ the 3.8....

just another quick question about the battery light. when it comes on, is it absolutely the alternator or could it possibly be the battery????? i took it to a shop, and the mechanic said he charged the battery and tested everything and he determined my problem to be the alternator. the only problem i had was when i went to start the car, it acted as though the battery was still dead and never got a charge at all. i just want to make sure what this mechanic said is true, because i dont think he did anything at all and just decided to tell me its the alternator when i came back to his shop to pick up my tbird.

If it was the alternator the car would die after you jump started it. To me this sounds more like a battery problem or even a short in the system somewhere. The short could be sucking the juice out of the battery and draining it faster than you can charge it. It might also be the voltage regulator on the alternator. I would take the battery to a auto parts store to have it tested. If that checks out good then you can try to take the alternator to have that tested too. I would have to think it is one of the other things that mentioned though.