1972 Ignition problems
Thread Starter
|
Freshman User
Joined: Apr 2012
Posts: 30
Likes: 0
1972 Ignition problems
1972 Ford F750 with a 391. It was running smoothly and sputtered to a stop. I replaced all ignition components but it will not even try to crank. It's getting fuel. (New points, condenser, coil, distributor, rotor, plug wires, ignition switch) I set the points to .016 which I am told is about right. I have put it together and taken it apart several times for several days. I have even tried hot wiring it and put 3 different sets of each of the components I have in it and I am completely stumped. The closest I have come to getting anything out of it is blue spark from the coil wire to block a few times. Then later red spark from the coil wire with none coming out of the distributor either of those times.
Lead Driver
Joined: Jan 2003
Posts: 9,893
Likes: 12
From: Ohio
There is a problem with your rotors? If it is not transfering to plug wires, it has to stop there. Or your caps are screwed up at the center point terminal(for coil wire) and is not transfering to rotor.
Make sure you can see a wear spot where the center terminal is touching the rotor tab.
I've had same head scratching problem with my '69 f100 a couple times. It would quit, nothing would make it run. Change everything out to known good parts, still nothing. Swap everything back and it would magically run?? Run fine for years, then strangely do it again. I'm still stumped over it(though it's been fine for about 3 yrs now).
Make sure you can see a wear spot where the center terminal is touching the rotor tab.
I've had same head scratching problem with my '69 f100 a couple times. It would quit, nothing would make it run. Change everything out to known good parts, still nothing. Swap everything back and it would magically run?? Run fine for years, then strangely do it again. I'm still stumped over it(though it's been fine for about 3 yrs now).
Posting Guru
Joined: Aug 2005
Posts: 1,069
Likes: 1
1972 Ford F750 with a 391. It was running smoothly and sputtered to a stop. I replaced all ignition components but it will not even try to crank. It's getting fuel. (New points, condenser, coil, distributor, rotor, plug wires, ignition switch) I set the points to .016 which I am told is about right. I have put it together and taken it apart several times for several days. I have even tried hot wiring it and put 3 different sets of each of the components I have in it and I am completely stumped. The closest I have come to getting anything out of it is blue spark from the coil wire to block a few times. Then later red spark from the coil wire with none coming out of the distributor either of those times.
FTE Leadership Emeritus
Joined: Jul 2002
Posts: 42,561
Likes: 421
From: Long Island USA
If you aren't getting a consistent spark from the coil wire to ground, there's something wrong with either the points, condensor, coil, or voltage getting to these parts.
Before you do anything, with the distributor cap off, crank the engine and check that the points are actually opening and closing. And, of course, that the distributor shaft is turning in the first place
Then, start simple - get a volt meter (better to get a new-fangled digital one from Radio Shack, doesn't need to be more than the basic model), and with the points OPEN and the key on - check the voltage between ground and the (+) side of the coil. Should be somewhere north of 8 volts or thereabouts because of the ballast resistor. If that checks good, continue on...
With the key off, and the points open, check the resistance (ohms) between the (-) side of the coil and ground. It should be infinite after a few seconds (condensor might cause a momentary blip). Turn the engine until the points are closed, recheck - should be 0 or close to it. If good, continue...
I suspect a bad connection somewhere, low voltage, or something else, report back all that you find and we'll continue working on it with you...
When you changed all those parts, was the coil replaced too?
Before you do anything, with the distributor cap off, crank the engine and check that the points are actually opening and closing. And, of course, that the distributor shaft is turning in the first place
Then, start simple - get a volt meter (better to get a new-fangled digital one from Radio Shack, doesn't need to be more than the basic model), and with the points OPEN and the key on - check the voltage between ground and the (+) side of the coil. Should be somewhere north of 8 volts or thereabouts because of the ballast resistor. If that checks good, continue on...
With the key off, and the points open, check the resistance (ohms) between the (-) side of the coil and ground. It should be infinite after a few seconds (condensor might cause a momentary blip). Turn the engine until the points are closed, recheck - should be 0 or close to it. If good, continue...
I suspect a bad connection somewhere, low voltage, or something else, report back all that you find and we'll continue working on it with you...
When you changed all those parts, was the coil replaced too?
Thread Starter
|
Freshman User
Joined: Apr 2012
Posts: 30
Likes: 0
I did put a new coil on it. I put another new condensor on today too: a little more costly one. Getting a definite red spark now, it's just not going out of the distributor. I'll try your check procedure and post results on here. thanks for trying to help.
Trending Topics
FTE Leadership Emeritus
Joined: Jul 2002
Posts: 42,561
Likes: 421
From: Long Island USA
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
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
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Thread Starter
|
Freshman User
Joined: Apr 2012
Posts: 30
Likes: 0
If you aren't getting a consistent spark from the coil wire to ground, there's something wrong with either the points, condensor, coil, or voltage getting to these parts.
Before you do anything, with the distributor cap off, crank the engine and check that the points are actually opening and closing. And, of course, that the distributor shaft is turning in the first place GOOD THERE
Then, start simple - get a volt meter (better to get a new-fangled digital one from Radio Shack, doesn't need to be more than the basic model), and with the points OPEN and the key on - check the voltage between ground and the (+) side of the coil. Should be somewhere north of 8 volts or thereabouts because of the ballast resistor. If that checks good, continue on... GOOD THERE
With the key off, and the points open, check the resistance (ohms) between the (-) side of the coil and ground. It should be infinite after a few seconds (condensor might cause a momentary blip). Turn the engine until the points are closed, recheck - should be 0 or close to it. If good, continue... GOOD THERE
I suspect a bad connection somewhere, low voltage, or something else, report back all that you find and we'll continue working on it with you...
When you changed all those parts, was the coil replaced too?
Before you do anything, with the distributor cap off, crank the engine and check that the points are actually opening and closing. And, of course, that the distributor shaft is turning in the first place
GOOD THEREThen, start simple - get a volt meter (better to get a new-fangled digital one from Radio Shack, doesn't need to be more than the basic model), and with the points OPEN and the key on - check the voltage between ground and the (+) side of the coil. Should be somewhere north of 8 volts or thereabouts because of the ballast resistor. If that checks good, continue on... GOOD THERE
With the key off, and the points open, check the resistance (ohms) between the (-) side of the coil and ground. It should be infinite after a few seconds (condensor might cause a momentary blip). Turn the engine until the points are closed, recheck - should be 0 or close to it. If good, continue... GOOD THERE
I suspect a bad connection somewhere, low voltage, or something else, report back all that you find and we'll continue working on it with you...
When you changed all those parts, was the coil replaced too?
still stumped after all that.
Earl
Posting Guru
Joined: Aug 2005
Posts: 1,069
Likes: 1
I bought a new coil about a month ago and the - and + were reversed on the coil. It was for my 73 Mustang. I reversed the wires and now it's ok. I have the + going to distributor. Made in Mexico.
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
Likes: 784
From: Simi Valley, CA
(the one that goes from the points to the (-) on the coil)Look inside the dizzy for the short primary wire. The 1957/66 original was bare, 1967 and later version has a black coating on it. The wire could have snapped under the coating.
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
Likes: 784
From: Simi Valley, CA
Originally Posted by earl6969
Do you know where the resistor is?
COLF-12250-A .. Resistor Wire-Ignition Coil (Motorcraft DY-37).
61.49" long / Color coded PINK / 1.30-1.40 ohms resistance / #16 gauge wire.
Or:
D1AZ-12250-A .. Resistor Wire-Ignition Coil (Motorcraft DY-84-A).
60" long / Color coded RED with GREEN stripes / 1.30-1.40 ohms resistance / #16 gauge wire.