Charging System Problems
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Senior User
Joined: Dec 2001
Posts: 207
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From: Brockport USA
Charging System Problems
I recently purchased a 1979 F250 4x4 Tow Truck. The truck has a 400ci with a 4 speed, Western plow, & a Holmes 440 wrecker on the back. When the truck is running, if I disconnect the positive terminal on the battery, the engine dies, like the alternator is not charging. The alternator looks new, and I took it off and had it checked. I also replaced the voltage regulator. Ive replaced any connections I think might be bad, but the truck still won't charge. Any suggestions where to look next?
Thanks in advance
Wrecker
Thanks in advance
Wrecker
Cargo Master
Joined: Sep 2001
Posts: 3,135
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From: Canada
Charging System Problems
this might sound stupid but is the battery good, and there might be a bad connection to lights, or something cause it to drain the battery. my neibour drives a ponitac van and he had the same problem. jurned out it was a bad connection in the power locks. go figure
Joseph
Joseph
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Joined: Jan 2002
Posts: 17
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From: Coeur d' Alene USA
Charging System Problems
Check the post on Jan 20 by Dougx. I went through the same thing and got on the right track with some help from this forum.I tried to post the results earlier but it would not go through. Mine happened to be a plow truck as well.Everything was removed and checked like yours.I suspect that the carb has been changed on yours also.I ended up finding two problems. One the field and stator wires were reversed. The field is just next to the large battery post on the back of the alternator. The other problem was when they changed out the carb and unplugged the electric choke element that also disconnects the power to the alternator field. Mine has a manual choke I just took the 2 prong rubber plug that hangs just below the wiring loom and connected the wires together and all worked fine.I found the problem with the choke first and when I ran the engine the output was full fielded because of the reversed wires. I would be curious if this is your problem. Please post the your findings or e-mail me. dougx75(No Email Addresses In Posts!)
Junior User
Joined: Jun 2000
Posts: 77
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From: Fridley, Minnesota
Charging System Problems
[updated:LAST EDITED ON 24-Jan-02 AT 00:55 AM (EST)]Just wondering if you installed the new voltage regulator and then to test it you took off the negitive battery terminal. You should not do that because it can fry the voltage regulator or alternator. I use to do that myself, but I learned from experience. Good luck.
Bob
Bob
Elder User
Joined: Sep 2000
Posts: 718
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From: Golden ,CO USA
Charging System Problems
ive been having the same problem with my battery going dead. i think i found the problem with the wat the dual battery isolater was hookd up. but now that u mention your trouble being with your electric choke, its got me thinking. there was/ is a edlelbrock 600 on my engine with electric choke. the wires for the electric choke are right by the carb. but there is only one wire connecting it to the carb. is the other wire just a ground wire?? the elec choke on the carb is grounded to the carb mount bolt. should it be tied in with the original harness for the elec choke?????
'75 F-100 4x4, 4" lift
16x38.5x15 super swamper TSL
390 w/ cam,headers,
and 4 barrell edelbrock
TRIED TRUE and FORD BLUE
'75 F-100 4x4, 4" lift
16x38.5x15 super swamper TSL
390 w/ cam,headers,
and 4 barrell edelbrock
TRIED TRUE and FORD BLUE
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New User
Joined: Jan 2002
Posts: 17
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From: Coeur d' Alene USA
Charging System Problems
On my '78 there are two wires in rubber plug,one is the 12v from the ignition coming in the other is the one that goes to the alternator. I have not seen a stock set up to see how they are connected. I just took a scotch lock and spliced the two together and it works great.
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Thread Starter
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Senior User
Joined: Dec 2001
Posts: 207
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From: Brockport USA
Charging System Problems
Thank you for responding to my post... I really appreciate it. If you don't mind, I have 2 questions about your reply. I think your are right about both the wires switched, and the Choke. I currently have a yellow wire with a black stripe going from a plug in the wire harness to the field next to the large battery post on the alternator.I also have an orange wire going from the voltage requlator to the "other" field on the back of the alternator. Is it Ok to switch just them and see what happens? Should I hook them back up one at a time? also My truck's choke is not hooked up. Can you please explain exactly where the 2 prong rubber plug is your talking about? Is it in the wire harness, on the friewall , just to the left of the carb? is it a flat plug, or is it more rounded?
I'm new at working on Fords.... Thanks for your help.
Wrecker
pmagrud1@rochester.rr.com
I'm new at working on Fords.... Thanks for your help.
Wrecker
pmagrud1@rochester.rr.com
Elder User
Joined: Sep 2000
Posts: 718
Likes: 0
From: Golden ,CO USA
Charging System Problems
the carb plug on mine is a flat rubber connecter with two wires coming out of it just to the left of the carb coming off the firewall. (as you are looking at the engine). so it is al right to splice the two wires into one????? and it wont hurt anything???
'75 F-100 4x4, 4" lift
16x38.5x15 super swamper TSL
390 w/ cam,headers,
and 4 barrell edelbrock
TRIED TRUE and FORD BLUE
'75 F-100 4x4, 4" lift
16x38.5x15 super swamper TSL
390 w/ cam,headers,
and 4 barrell edelbrock
TRIED TRUE and FORD BLUE
New User
Joined: Jan 2002
Posts: 17
Likes: 0
From: Coeur d' Alene USA
Charging System Problems
I can't tell you that for sure It did not hurt anything on mine. I have a suspicion that someone has changed my wiring somewhere that I can't spot it. Here is an update that I sent to someone else earlier.
Some of the info was provided by an earlier post as well.
I happened to run into a stock '79 bronco with a 400 today. I looked at it for a minute. The plug on the fire wall came out with 2 prongs but only one went to the choke the other was not connected to anything and was not internally joined. The choke wire that also goes to the stator will only come alive after the engine is running ans charging. The field wire goes directly from the alt to the v-reg`. Only the 3 wires on the right side of the reg were used as you look at the plug. I think the 4th is an idiot light. Just thought I'd pass this on.
Some of the info was provided by an earlier post as well.
I happened to run into a stock '79 bronco with a 400 today. I looked at it for a minute. The plug on the fire wall came out with 2 prongs but only one went to the choke the other was not connected to anything and was not internally joined. The choke wire that also goes to the stator will only come alive after the engine is running ans charging. The field wire goes directly from the alt to the v-reg`. Only the 3 wires on the right side of the reg were used as you look at the plug. I think the 4th is an idiot light. Just thought I'd pass this on.