I was driving just now and heard a rock or something hit the bottom of my car but nothing big and a little while later I accelerated and felt like the headlights went really bright and dimmed down. The battery voltage read 12. Then when I took my foot off the gas the voltage went back up to 12.5-13. Then accelerating it went back down to 12. Coincidentally my idle RPM went from my normal 750 to 1000. Then I noticed that the A/F gauge started flashing and wouldn't read the A/F but car was running well.
Your car is modded pretty heavily ... do you still have an external voltage regulator like it came from the factory? Had a problem with the headlights blinking on and off ... turned out to be a regulator that was allowing overcharging, and the circuit breaker in the headlight switch was cycling them. It end up frying because I ran it too long. If you changed alternators, possibly you have a newer one with an internal regulator?
Went to start it again today, no trouble starting. When it first started I could see the electrical voltage going up to my normal 13.5-14 and then it dropped right down to 12 after a minute. I had no problems driving around on the car. Then voltage came down to like 11.8 and the A/F gauge went out again and my RPM started coming up to 1000 from 750.
The idle keeps ramping up? .... your car is carbed, right? ... or is it fuel injected? One idea that I have is that possibly the contacts in the alt are worn.... make good enough contact at idle, but too weak to do so at higher rpms. Someone who knows more about rebuilding one could verify if this is correct thinking. I just bolt them on, never rebuilt one ... rebuilt a starter once, though.
You stated that something bounced up and hit the car??? A stone or something to that effect???? Check your O2 sensor harness and battery cables under the car (your batt is in the trunk right?) see if something got nicked and is shorting out on the floor pan/frame rail/header...Good luck!!!
Try these basic Battery/Alt/Voltage Reg checks, before you go deeper: Sounds like a bad Voltage Regulator, or Bad Alternator, but a number of things could be the culprit. 1. Measure the DC Voltage across the Battery, with engine off, and no accessories running. (Hopefully around 12vdc) Also move the negative meter lead to chassis ground, and look for the same reading. 2. Start the car, leave in park, and with the headlights off, and all accessories off...measure the DC Voltage across the Battery terminals. (Hopefully around 14vdc) Also move the negative meter lead to chassis ground, and look for the same reading. 3. With engine still running...switch your Voltmeter to read AC voltage, and measure the AC Voltage across the Battery. (Should read less than .5 Vac or less than 1/2 Volt ac) 4. With engine still running...Switch your voltmeter between DC and AC, and turn the headlight on, and measure the DC and the AC reading across the Battery. (Hopefully still close to same readings) Let us know how these readings checkout.
I had the maverick towed to the shop and Bryant tested the post with the car running, I had 11.8 volts, I had about the same on the battery that I checked earlier. Disconnected the alt while the car was running and was getting same voltage on the electrical terminals so the alt was getting a signal which means wires were good but alt was bad. We think it might be the fact that I never installed a resistor wire/light in there after we took the dash off. So we'll do that when we put the alt back in.
Okay. Make sure you don't disconnect the new alternator, while the car is running, as this can damage the diodes in the alternator. Good work Mashori. Sorry to to hear about vehicle accident with Bryant. You guys take care.
