79 f100 starting problems - Ford Truck Enthusiasts Forums



1973 - 1979 F-100 & Larger F-Series Trucks Discuss the Dentsides Ford Truck

79 f100 starting problems

Reply
 
 
 
Thread Tools Search this Thread
  #1  
Old 09-03-2011, 07:19 PM
skotrod1 skotrod1 is offline
New User
Thread Starter
 
Join Date: Aug 2011
Location: fingerlakes,NY
Posts: 4
skotrod1 is starting off with a positive reputation.
79 f100 starting problems

Hi, Going through this forum I've found a lot of good info. I hope one of you can give me some idea or cure for my starting problem. I have a 79 F100 302 AT 2WD. The truck on occasion will turn over and start but when I back the key off to the run position the truck shuts off. Eventually it will stay running and not give a problem for a few days. Today I went through this and when I got home I shut the truck off but had power to the dash, a light (I didnt pay attention to which light) was on. I tried the key again, light stayed on, I disconnected the battery. Over the past couple of weeks I've changed the Ignition switch, A new Ign module from NAPA, cleaned the contacts to the coil, The starter solinoid is new, the Alt has been changed to a 1 wire with internal voltage reg. I've checked the fusible links OK. When the truck is in the fail mode there are 2 red wires with green tracers from a terminal on the back of the ign switch, one of these gets so hot it will burn your finger. Thats about it, any ideas would be appreciated. Thanks Skotrod
Reply With Quote
  #2  
Old 09-04-2011, 10:17 PM
skotrod1 skotrod1 is offline
New User
Thread Starter
 
Join Date: Aug 2011
Location: fingerlakes,NY
Posts: 4
skotrod1 is starting off with a positive reputation.
I'm surprised no one has offered up any info. I know there are a lot of similar treads but none answer my problem. Any ideas? Thanks again, Skotrod
Reply With Quote
  #3  
Old 09-05-2011, 02:09 PM
skotrod1 skotrod1 is offline
New User
Thread Starter
 
Join Date: Aug 2011
Location: fingerlakes,NY
Posts: 4
skotrod1 is starting off with a positive reputation.
Bump, someones gonna post sooner or later.
Reply With Quote
  #4  
Old 09-05-2011, 04:38 PM
Richtertrevor78's Avatar
Richtertrevor78 Richtertrevor78 is offline
New User
 
Join Date: May 2011
Posts: 4
Richtertrevor78 is starting off with a positive reputation.
With all the new parts you have thrown at the truck, recheck the grounds to the parts you changed out. When I first got mine, I caught hell figuring out that my starter was grounding out from the inside wiring touching the frame of the starter. All kinds of wires got hot and all I did was replace the voltage regulator and starter solinoid. It seems like ground will be the cure (and not a wire), a screw that is also the component ground. Some of the screws going into fender walls seem tight but still kind of have some play, they are more important than they look. Hopefully its that easy.
Reply With Quote
  #5  
Old 09-11-2011, 04:58 PM
fmc400's Avatar
fmc400 fmc400 is offline
MSEE
 
Join Date: Apr 2004
Location: Austin, TX
Posts: 10,386
fmc400 has much to be proud offmc400 has much to be proud offmc400 has much to be proud offmc400 has much to be proud offmc400 has much to be proud offmc400 has much to be proud offmc400 has much to be proud offmc400 has much to be proud offmc400 has much to be proud offmc400 has much to be proud of
Sounds like a problematic connection at the ballast, which is responsible for powering the ignition coil when the key is turned to RUN.

The fact that there is a wire getting so hot that it burns your finger means you need to disconnect the battery, and not reconnect it until you have solved the problem. The wire that's getting hot sounds like it is the ballast. Does it say "DO NOT SPLICE?" If so, that's the one. It's highly likely that the two issues are related. My guess would be the ballast is shorted to ground somewhere along the wiring harness. 9 times out of 10, this is because someone has modified the truck's wiring somehow. Start checking.
Reply With Quote
  #6  
Old 09-12-2011, 10:05 AM
JoeHarbourJets JoeHarbourJets is offline
Senior User
 
Join Date: Sep 2007
Posts: 124
JoeHarbourJets is starting off with a positive reputation.
skotrod: you wrote: "When the truck is in the fail mode there are 2 red wires with green tracers from a terminal on the back of the ign switch, one of these gets so hot it will burn your finger."

Are both these actually wired to to the switch? I don't have a 79 myself, and something may be different from mine, but I think there should only be one red/green wire, which I'm pretty sure goes to the instrument lights.
Reply With Quote
  #7  
Old 09-16-2011, 08:35 PM
skotrod1 skotrod1 is offline
New User
Thread Starter
 
Join Date: Aug 2011
Location: fingerlakes,NY
Posts: 4
skotrod1 is starting off with a positive reputation.
Ive been real busy the past couple of weeks and hav'nt had time to keep up with the forum or work on the truck. Thanks for the reply's, Ill try to check on some of the suggestions. joe harbor jets, yes both wires come from one terminal on the back of the ignition switch, all I have is a haynes manual and the wiring diagrams are not detailed enough, and I don't really trust them to be 100% accurate.
Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
'88 4.9L no spark, among other electrical issues Rwm8082 1987 - 1996 F150 & Larger F-Series Trucks 3 01-30-2017 01:39 PM
Short somewhere'1976 F-150 4x4 auto 351 cushing 1973 - 1979 F-100 & Larger F-Series Trucks 5 01-10-2017 01:36 PM
No power to alternator kujo3692 1987 - 1996 F150 & Larger F-Series Trucks 14 08-16-2016 06:49 PM
ignition wiring questions scottlathrop 1961 - 1966 F-100 & Larger F-Series Trucks 8 03-16-2016 11:00 AM
Starting Problems scalhoun 335 Series- 5.8/351M, 6.6/400, 351 Cleveland 6 02-10-2001 10:40 PM


Go Back   Ford Truck Enthusiasts Forums >

Tags
79, f100, ford, grounding, problems, regulator, starting, stater, voltage

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Forum Jump


All times are GMT -5. The time now is 07:58 PM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.