Hello,
I would greatly appreciate any help on this...
Yesterday I noticed that dash battery light came on if I run less then 2000 rpms. Everything looks OK if I have more than 2000 rpms. And it doesn't lit, it *sort of* blinks... Yes, it blinks...
In addition I noticed that my idle rpms changed. Intead of 500 I have 800-900 now...
I just added a bottle of Chevron Techron and still have it in the tank. Trying to clean up the fuel system to get rid of slight pinging I have... Close to 1/4 tankful already, already done it sort of... And while having this in the tank I have O/D off trying to increase rpms. I thought that it might help getting rid of carbon deposits...
Does any body knows what might be the problem???
Any input would be great!
________
'97 4.6L supercab F-150 around 90000 miles.

 

I do not think that the Chevron treatment is causing the problems. Sounds more like a alternator or battery problem. If it's the OEM battery my suggestion is to change it wether it is good or not. IMO the OEM motorcraft battery is junkand I personally would hate to get stranded in the cold with a dead battery. Have someone test your alt, and make sure it's up to peak performance.
What throws a loop in the plans is the idle change. I am not for sure if or how the ALT would change your RPM's that much. An RPM change like that has to be because of a sensor or I could be wrong.

 

Thanks KYFordFreak!
This morning I tried going to work having the same problem and somewhere in a middle the radio stopped working first and then all lights dimmed to almost nothing. I decided to return and get as close to my place as I can.
After around 30 min driving the car stalled. I was lucky I had time to pull over to a parking spot. 2-3 miles away from the destination. Around 5 am )
I had the truck towed to a shop and they say that it's the alternator.
Going to put a new one (130 amps) and along with this to change fuel filter ('cause I am in a shop any way)
I was kinda surpised that you run from both alt and battery when you drive. I thought the alt only so you have some time in reserve... Aparently you don't...
Thank again!
_____
'97 F-150 supercab, 90000 miles

 

Sorry to hear about the trouble, glad you found the problem. From the way I understand it. The alt supplies the battery, all your stuff essentially runs from the battery, it's just that your alt should put out at least 13.8-15 volts to keep the battery around a perfect 12.6v. When the alt fails to do this you are running on battery power, most batteries will usually have at least 45 minutes reserve to them, but with all the electronics in newer vehicles I would say whatever reserve you have will go fast. I noticed today that my alt has a slight bearing squeel and will probably be replacing mine soon too. Don't forget to change out old belts too. Good luck.