Truck.. died on me
11-07-2007, 09:40 AM
#1
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Truck.. died on me
I have an 89' F150 with a 302.
My battery has been on its last leg for while now and it finally went dead.
All I had to put in it was this big everstar marine maxx battery.
When I put the batter in, the truck cranked right up but the voltage stayed around 12 volts max even when running. Which from logic tells me that the old battery might have been going dead from the alt not charging properly. Anyways I was driving down the highway when the truck started bogging down sputtered when you hit the gas and didn't want to "go". I pull it over and it bearly wants to start and the light are dim, it will start but it still bogs down when you accelerate.
My main question is.
When your alt goes out will the vehicle not run.?
I figure the little juice on the battery will alow it to run...
My battery has been on its last leg for while now and it finally went dead.
All I had to put in it was this big everstar marine maxx battery.
When I put the batter in, the truck cranked right up but the voltage stayed around 12 volts max even when running. Which from logic tells me that the old battery might have been going dead from the alt not charging properly. Anyways I was driving down the highway when the truck started bogging down sputtered when you hit the gas and didn't want to "go". I pull it over and it bearly wants to start and the light are dim, it will start but it still bogs down when you accelerate.
My main question is.
When your alt goes out will the vehicle not run.?
I figure the little juice on the battery will alow it to run...
11-07-2007, 10:25 AM
#2
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Did you test the old battery after charging it on a charger? It may be that your alternator output has been on a long slide down and the battery may be savable.
An alternator should be putting out 12.8 - 14.2 volts or so when charging, depending on how much its loaded up.
I've been told it's bad practice to use the alternator to charge a very-low battery - puts a lot of strain on the alt.
Does your truck have the voltmeter gauge? If so, what was it reading when it starting sputtering, etc.?
In answer to your question - typical alternator failures should allow the truck to run off the battery until the voltage drop is too much.
I'm thinking somewhere in the 10-11 volt range, you will start seeing problems. Catastrophic failures that result in a dead short are another thing - but then you should have been able to notice this.
Just speculating, but I would think fuel injectors and spark voltage would start wigging out as the voltage drops. Not sure what voltage the computer will operate satifactory down to.
An alternator should be putting out 12.8 - 14.2 volts or so when charging, depending on how much its loaded up.
I've been told it's bad practice to use the alternator to charge a very-low battery - puts a lot of strain on the alt.
Does your truck have the voltmeter gauge? If so, what was it reading when it starting sputtering, etc.?
In answer to your question - typical alternator failures should allow the truck to run off the battery until the voltage drop is too much.
I'm thinking somewhere in the 10-11 volt range, you will start seeing problems. Catastrophic failures that result in a dead short are another thing - but then you should have been able to notice this.
Just speculating, but I would think fuel injectors and spark voltage would start wigging out as the voltage drops. Not sure what voltage the computer will operate satifactory down to.
11-07-2007, 10:48 AM
#3
Senior Member
Sounds like a bad alternator. I agree the bad battery more in likely killed the alt. And like mentioned, when the alt goes out, the vehicle will run until the battery drains so low it can run everything.
Also an alt can be bad even though it charges, if the regulator goes out. Will charge like normal, but battery will drain when vehicle is shut off. Most time have to jump it in when it sits for any length of time. But vehicle runs fine when started..
Also an alt can be bad even though it charges, if the regulator goes out. Will charge like normal, but battery will drain when vehicle is shut off. Most time have to jump it in when it sits for any length of time. But vehicle runs fine when started..
11-07-2007, 08:13 PM
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Figured it out guys.
The original reason why it wasn't goin very far. Is my dad had put gas in the wrong fuel tank.. the one i dont use because of the guage and have never used. My dad swore up and down he put gas in the rear tank. But It started right up and ran on the front tank. My voltage is sitting at 11.5 running... new alternator is needed )-:
The original reason why it wasn't goin very far. Is my dad had put gas in the wrong fuel tank.. the one i dont use because of the guage and have never used. My dad swore up and down he put gas in the rear tank. But It started right up and ran on the front tank. My voltage is sitting at 11.5 running... new alternator is needed )-:
04-29-2008, 12:11 AM
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voltage regulator?
i am new to the forum and having this same type of problem. i have put in a new alternator and battery in my 95 f-150 but am still having low running volt and the battery said 11.8 volt last i tested it. everything else sound the same the thing just crapped out on me on my way home one day.if the regulator is on the firewall i know it as voltage regulator and probably needto chang it? otherwise i have had no problems with my ford and love the truck...
