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Freshman User
Joined: Dec 2012
Posts: 44
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Just replaced the battery on my 86 F250 7.5L, about 3 months ago.
Everything was running well until last week, when I would turn the ignition key and there was a slight hesitation, but the engine would turn over.
Went to start it this morning and it was completely dead, nothing was left on, so what do I need to fix?
Thanks
Everything was running well until last week, when I would turn the ignition key and there was a slight hesitation, but the engine would turn over.
Went to start it this morning and it was completely dead, nothing was left on, so what do I need to fix?
Thanks
Elder User
Joined: May 2012
Posts: 978
Likes: 1
From: Covington VA
Its possible your alternator went bad and you was running on battery power and drained it. I think these are old enough for that to happen.
Anyway jump it and let it run a minute. Unhook the cables and watch it for 10 or 15 minutes. If it dies your alternator is bad.
If not its the battery. New ones can be bad too. As long as its running take it to advance or autozone and have them test it.
Or if you have a volt meter check the battery cables while its running. Should have about 13.5+ if its charging.
If you cant jump it its possibly the solenoid or maybe the starter up and quit. Or a ground or + cable vibrated loose.
Anyway jump it and let it run a minute. Unhook the cables and watch it for 10 or 15 minutes. If it dies your alternator is bad.
If not its the battery. New ones can be bad too. As long as its running take it to advance or autozone and have them test it.
Or if you have a volt meter check the battery cables while its running. Should have about 13.5+ if its charging.
If you cant jump it its possibly the solenoid or maybe the starter up and quit. Or a ground or + cable vibrated loose.
Fleet Mechanic
Joined: Jul 2011
Posts: 1,916
Likes: 4
Please, do not do this. If it's a Chevrolet, you can do this. Doing this to a Ford will ruin the truck.
Optimal voltage on the battery with the motor running is 14.2 volts.
If your truck has "idiot lights", check to see if the battery light is on while the motor is running. If so, it's either a bad alternator or a burnt up voltage regulator.
A Ford alternator has a diode on the inside that can burn up and cause a battery drain with the vehicle shut off.
Check to make sure your battery clamps and cables are rust free and clean first. Unhook them and clean them, then reinstall and tighten them up.
Hesitation on cranking can be a low battery, failings starter, poor connections, etc. So eliminate basic issues first.
https://www.ford-trucks.com/forums/1...e-running.html
Laughing Gas
Joined: Sep 2012
Posts: 1,100
Likes: 6
From: Georgia
An alternator needs a battery to regulate the voltage, it doesn't matter the car make. Without the battery to help regulate the alternator voltage you can burn out diodes in the alternator, not to mention wreck voltage sensitive components. If you possibly have a flakey alternator that you're testing then then you're likely to cause even more damage because the issue could be a bad diode to start with. Rev the engine with them disconnected and you could instantly send 35 volts through the electrical system.
The "remove the cable" test is a holdover from the days when vehicles had generators, and it was ok to run it without a battery. Technology changed and some practices needed to change.
The "remove the cable" test is a holdover from the days when vehicles had generators, and it was ok to run it without a battery. Technology changed and some practices needed to change.
Elder User
Joined: May 2012
Posts: 978
Likes: 1
From: Covington VA
Well when i did it we were starting my truck or a different on then putting the dead battery back in. We were 16/17 or so and never thinking to get jumpers to carry. I only thought they had to do quit because some computers wouldnt run without a battery.
Thank yall for the history lesson.
Thank yall for the history lesson.
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