New here with electrical problem
Thread Starter
|
New User
Joined: Jan 2015
Posts: 4
Likes: 0
New here with electrical problem
Hey, new guy with a 79 f150 with a 400m. It has been having some electrical problems. It keeps killing batteries just sitting. I replaced the igniton cylinder hoping it just wasnt turning off, start with the easy things right? But it still kills batteries. I did the test for battery draining in the thread at the bottom of my post and the test light was bright. I pulled each individual fuse but the light didnt change. I then checked the voltage as it was running and the battery was at about 12.4v and while running you could watch the voltage drop. My best guess is a bad voltage regulator but am not sure. Any help is appreciated, thanks
https://www.ford-trucks.com/forums/1...eps-dying.html.
https://www.ford-trucks.com/forums/1...eps-dying.html.
Hotshot
Joined: Apr 2009
Posts: 14,333
Likes: 247
From: Stanley, VA
With the engine running, you should get ~14 volts for the charging system to be working properly. 12.4 volts won't keep the battery charged.
It could be the voltage regulator but pull the alternator and take it to the parts store and have them test it.
There are a few circuits in the truck that aren't fused so if there's a short in one of them that's draining the battery, that wouldn't show up in the "fuse pulling" test.
Another place that could be causing the drain is the alternator. If the diodes short, that will also drain the battery.
Good luck and welcome to FTE.
It could be the voltage regulator but pull the alternator and take it to the parts store and have them test it.
There are a few circuits in the truck that aren't fused so if there's a short in one of them that's draining the battery, that wouldn't show up in the "fuse pulling" test.
Another place that could be causing the drain is the alternator. If the diodes short, that will also drain the battery.
Good luck and welcome to FTE.
Thread Starter
|
New User
Joined: Jan 2015
Posts: 4
Likes: 0
Ok I will pull the alternator and get that tested. I realized that it obviously wasnt charging but I believe its a fairly new alternator. I am sure it is remanufactured Napa crap though so thats probably why.
Thread Starter
|
New User
Joined: Jan 2015
Posts: 4
Likes: 0
I think you are right. I had the alternator tested and it came up bad so I got a new one. The voltage at the battery is now 17.7 volts so at least its charging. Now on to replace that voltage regulator.
Thread Starter
|
New User
Joined: Jan 2015
Posts: 4
Likes: 0
Ok would it be a good idea to replace it with a more modern regulator? The last post says that you can replace the regulator with a newer one. https://www.ford-trucks.com/forums/1...regulator.html Also, are there certain brands to stay away from?
Hotshot
Joined: Apr 2009
Posts: 14,333
Likes: 247
From: Stanley, VA
Ok would it be a good idea to replace it with a more modern regulator? The last post says that you can replace the regulator with a newer one. https://www.ford-trucks.com/forums/1...regulator.html Also, are there certain brands to stay away from?
Seeing as your truck is a '79, it should have come with the later solid state regulator.
I would use a quality replacement, my preference would be either Ford FOPZ-10316-A or Motorcraft GR-540-B.
Thread
Thread Starter
Forum
Replies
Last Post
BDodson
1973 - 1979 F-100 & Larger F-Series Trucks
4
Apr 5, 2018 05:26 PM
