Electrical issue. 3G and Points
Thread Starter
|
Lead Driver
Joined: Jul 2011
Posts: 8,679
Likes: 191
From: On the Edge of the Desert
Electrical issue. 3G and Points
OK so I got the engine back in the truck and running.
It runs pretty smooth with the points and just the battery, however when I hook up the 3G alternator, it starts running erratically.
Perhaps the alternator voltage is over powering the points/condenser?
It runs pretty smooth with the points and just the battery, however when I hook up the 3G alternator, it starts running erratically.
Perhaps the alternator voltage is over powering the points/condenser?
Hotshot
Joined: Mar 2013
Posts: 14,255
Likes: 199
From: Phoenix, Az.
Sounds like something is back feeding electricity. Engine ground cable to firewall got good connection? Internal short in the 3G? What is the 3G's red/green "I" terminal wire connected to?
I got to go look at a friend's Van oil leak and get some lunch. Keep me posted via text.
I got to go look at a friend's Van oil leak and get some lunch. Keep me posted via text.
Thread Starter
|
Lead Driver
Joined: Jul 2011
Posts: 8,679
Likes: 191
From: On the Edge of the Desert
Replaced alternator, still does it.
On a whim, I removed the points and reinstalled my pertronix kit that I wasn't sure was good or bad. Well it's bad, it wouldn't start at all.
I'm thinking it might be a bad condenser. Not really sure though since it does run.
On a whim, I removed the points and reinstalled my pertronix kit that I wasn't sure was good or bad. Well it's bad, it wouldn't start at all.
I'm thinking it might be a bad condenser. Not really sure though since it does run.
Cargo Master
Joined: Sep 2012
Posts: 3,061
Likes: 39
From: Laramie, WY
This is really weird one...if the condenser is bad the engine would run the same with or without the condenser. It would have a hard time running either way. Have you tried unhooking the new alternator to see if the engine will go back to running fine? I've never seen an alternator cause that kind of problem.
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
What else is there? Either the ignition coil or, the condenser, practically has to be at fault here.
It may be the running voltage of 14.X volts with the alternator connected pushes the primary coil ignition voltage and kickback just over and it is shorting out internally. Defective condensers are certainly not rare these days.
Total WAG of course, and prepared to be wrong. Interesting problem.
Thread Starter
|
Lead Driver
Joined: Jul 2011
Posts: 8,679
Likes: 191
From: On the Edge of the Desert
Turns out my theory was correct. Or at least partly....
The condenser must have been weak, because the higher voltage from the alternator would cause it to start acting up. Then it started doing it even without the alternator.
So, I got a new pertronix unit since my old one got burned out somehow. Put that in and it runs normal.
After 3 weeks and multiple headaches, chasing a compound problem,,,, dare I say,,, I fixed it????
The condenser must have been weak, because the higher voltage from the alternator would cause it to start acting up. Then it started doing it even without the alternator.
So, I got a new pertronix unit since my old one got burned out somehow. Put that in and it runs normal.
After 3 weeks and multiple headaches, chasing a compound problem,,,, dare I say,,, I fixed it????
Trending Topics
Fleet Mechanic
Joined: May 2001
Posts: 1,396
Likes: 4
From: Cupertino
Good. You got it fixed but we are sure curious about what the root cause was.
The ignition path is from the battery to switch to coil to points. The alternator kinda hangs off as an appendage.
A long shot:
The alternator has a bad ground or connection. It keeps throwing out ever higher volts to try to reach 14.3 but much higher voltage is reaching the primary, maybe blowing a condenser or module.
351, just for drill to close out: do a voltage check from the alternator case to the negative battery terminal. The right answer should be zero. Because it runs now doesn't mean you have solved the problem.
The ignition path is from the battery to switch to coil to points. The alternator kinda hangs off as an appendage.
A long shot:
The alternator has a bad ground or connection. It keeps throwing out ever higher volts to try to reach 14.3 but much higher voltage is reaching the primary, maybe blowing a condenser or module.
351, just for drill to close out: do a voltage check from the alternator case to the negative battery terminal. The right answer should be zero. Because it runs now doesn't mean you have solved the problem.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Thread Starter
|
Lead Driver
Joined: Jul 2011
Posts: 8,679
Likes: 191
From: On the Edge of the Desert
I checked all connections and whatnot. Alt is well grounded, no resistance between negative terminal and case, or charge lug and positive.
The root cause, I believe is because I have bypassed the resistance wire for the coil. So I was sending a full 12-13-14 volts through the system. As we all know they are made to run on 7-9 volts, so I knew I was pushing my luck, but it was only a temporary use before I went back to electronic.
The root cause, I believe is because I have bypassed the resistance wire for the coil. So I was sending a full 12-13-14 volts through the system. As we all know they are made to run on 7-9 volts, so I knew I was pushing my luck, but it was only a temporary use before I went back to electronic.
Thread
Thread Starter
Forum
Replies
Last Post
maytea
1973 - 1979 F-100 & Larger F-Series Trucks
5
Nov 26, 2017 06:23 PM
Jon351m
1973 - 1979 F-100 & Larger F-Series Trucks
5
Jan 18, 2013 05:49 PM