Won't fire, please help!

[msweb]

The big day has come and we're ready to fire the new motor but... No fire out of the coil when cranking. We've got about 8.5 volts @ the coil with the key off. Key in the start/run position voltaged changes to about 9 volts. Nothing coming out of the coil to the dizzy.

74, 302, Duraspark. New coil which checks out ok, "no external resistor needed".

Any ideas?

 

[msweb]

Update... 12v out of battery but only 8.7v coming out of the solenoid. Jumped 12v directly to the positive terminal of the coil but still no spark. Does the Duraspark module need a constant 12v so jumping 12v straight to the coil doesn't make a difference?

 

[Viperwolf1]

Should have 0V at the coil with the key OFF. Is this '74 duraspark wiring or later? What color insulator? Tell us more about the 8.7V. Where are you measuring?

 

[msweb]

Should have 0V at the coil with the key OFF. Is this '74 duraspark wiring or later? What color insulator? Tell us more about the 8.7V. Where are you measuring?

As far as I know, it's the Duraspark from 74 but the only reason I say that is because it's there and it looks like it's factory. The 12v is on the hot side of the solenoid from the battery, 8v is on the starter side with the key on, also at positive terminal of the coil.

I'll check on the color of the insulator and about to try another solenoid. Will be right back....

Also... This plug (below) was unplugged since I've owned and driven the truck and I have no idea what it should be hooked up to. It's in the main harness for the dizzy/coil and heads towards the firewall. I think it may have been a blue wire at some time...

 

[msweb]

replaced the solenoid, same thing. 8.75 volts at the I terminal with the key on.

Don't know about the color of the insulator... what exactly did you mean?

Here's the Duraspark -

 

[Jeepster]

"Don't know about the color of the insulator... what exactly did you mean?"

Where the wires go into the module the insulator comes in different colors. Not sure what color for a 74. I think wrong module?

You should have about 9v,at the coil,with the key on the run position with stock wiring (resistor wire from the ignition). A full 12v,at the coil,with the key in the start position (bypasses the resistor wire).

 

[Viperwolf1]

As far as I know, it's the Duraspark from 74 but the only reason I say that is because it's there and it looks like it's factory. The 12v is on the hot side of the solenoid from the battery, 8v is on the starter side with the key on, also at positive terminal of the coil.

I'll check on the color of the insulator and about to try another solenoid. Will be right back....

Also... This plug (below) was unplugged since I've owned and driven the truck and I have no idea what it should be hooked up to. It's in the main harness for the dizzy/coil and heads towards the firewall. I think it may have been a blue wire at some time...

Blue wire was for a carb mounted throttle solenoid. It's ok as is.

'74 wiring and module is different than later years. You might want to verify your harness-side wire colors and number of wires with this diagram. The module colors probably don't match if it's been replaced before.

 

[msweb]

I'll check the colors shortly but doubt thats the issue. It's the same one thats been in there and everything ran fine before swapping engines. I'll check it though...

 

[Viperwolf1]

replaced the solenoid, same thing. 8.75 volts at the I terminal with the key on.

Don't know about the color of the insulator... what exactly did you mean?

Here's the Duraspark -

Ok, thats a '74 module. Must be a CA Bronco originally.

Take a multimeter and make some measurements. Leave the key off and take the module connectors apart.

pin 4 to pin 5 resistance should be 1.0-1.5 ohms
pin 5 and the coil high tension terminal resistance should be 7,000-13,000 ohms
pin 8 to pin 7 resistance should be 400-800 ohms
pin 6 to ground resistance should be 0 ohms

Now turn the key ON and measure voltage.

Both pins 1 and 4 should have 12V

Turn the key OFF before reconnecting the connectors.

 

[msweb]

Ok, thats a '74 module. Must be a CA Bronco originally.

Take a multimeter and make some measurements. Leave the key off and take the module connectors apart.

pin 4 to pin 5 resistance should be 1.0-1.5 ohms
pin 5 and the coil high tension terminal resistance should be 7,000-13,000 ohms
pin 8 to pin 7 resistance should be 400-800 ohms
pin 6 to ground resistance should be 0 ohms

Now turn the key ON and measure voltage.

Both pins 1 and 4 should have 12V

Turn the key OFF before reconnecting the connectors.

Ok, looks like mine has in fact been replaced before and my numbers don't jive with what you have here. Not real sure about testing pin 4 to 5 or 7 to 8 in regard to truck side or module side so tested both sides on each. 4-5 was 0 on the module side, 3.5 on the truck side. 7-8 was 0 on the truck side and 970 on the module side.

With the key on, pin 1 was 0 and pin 4 was 12.

Guess all this means I need to try a new module? Wonder why it went bad over night? is it possible it was damaged while pressure washing the engine bay? That's all I could think of?

I'll get another module as soon as I can and test it. A very sincere thanks for your help!

 

[Viperwolf1]

Ok, looks like mine has in fact been replaced before and my numbers don't jive with what you have here. Not real sure about testing pin 4 to 5 or 7 to 8 in regard to truck side or module side so tested both sides on each. 4-5 was 0 on the module side, 3.5 on the truck side. 7-8 was 0 on the truck side and 970 on the module side.

With the key on, pin 1 was 0 and pin 4 was 12.

Guess all this means I need to try a new module? Wonder why it went bad over night? is it possible it was damaged while pressure washing the engine bay? That's all I could think of?

I'll get another module as soon as I can and test it. A very sincere thanks for your help!

Sorry I should have said harness side.

The 3.5 ohms on pins 4 ans 5 are a little high but you are measuring through a lot of wiring and several connectors so it may be ok.

I also screwed up when I said pin 1 and pin 4 for 12V. It should have been pin 3 and pin 4.

The most telling thing though is the 0 ohms on pins 7 and 8. That indicates a bad stator inside the distributor. I think that is where your problem is. You can verify by disconnecting the distributor connector and measuring ohms between the orange and purple wires. Still should be 400-800 ohms.

 

[msweb]

Ok, I'll have to wait till I can get an ohm meter now (Anthony just moved to AL as of 30 minutes ago, lol) and I'll check that. What would cause the stator to fail like that? Working fine before the engine was pulled and then not working at all? And it's a fairly new dizzy, probably less than 500 miles?

 

[msweb]

Ok, thats a '74 module. Must be a CA Bronco originally.

Why do you say CA Bronco for a 74? Any other way to verify that's where it's originally from? Wonder how it wound up in AL all the way from CA...

 

[Viperwolf1]

Usually they last a long time. I have seen the plastic around them crack probably from high heat. Being relativly new is a good reason to double check at the distributor itself. There's a chance the problem could be in the wiring between the distributor and module.

 

[Viperwolf1]

Why do you say CA Bronco for a 74? Any other way to verify that's where it's originally from? Wonder how it wound up in AL all the way from CA...

The only '74 Broncos that had the early duraspark were the ones sold in CA. CA had tighter emissions standards and Ford had to come op with the system to be able to sell cars/trucks in CA.

If you look on the VIN tag and find the DSO code it will tell you the area it was first sold in.

 

[msweb]

The only '74 Broncos that had the early duraspark were the ones sold in CA. CA had tighter emissions standards and Ford had to come op with the system to be able to sell cars/trucks in CA.

If you look on the VIN tag and find the DSO code it will tell you the area it was first sold in.

lol, screwed again. I don't have a VIN tag, just a VIN on my title

 

[Viperwolf1]

These are the DSO codes for '74.

DSO Code
11 Boston
12 Buffalo
13 New York
14 Pittsburgh
15 Newark
16 Philadelphia
17 Washington
21 Atlanta
22 Charlotte
23 Memphis
24 Jacksonville
25 Richmond
26 New Orleans
28 Louisville
41 Chicago
42 Cleveland
43 Milwaukee
45 Lansing
46 Indianapolis
47 Cincinnati
48 Detroit
52 Dallas
53 Kansas City
54 Omaha
55 St. Louis
56 Davenport
57 Houston
58 Twin Cities
71 Los Angles
72 San Jose
73 Salt Lake City
74 Seattle
75 Phoenix
76 Denver
83 Government
84 Home Office Reserve
87 Body Company
85 American Red Cross
89 Transportation Services
90's Export
A1 Mercury of Canada - Central
A2 Mercury of Canada - Eastern
A3 Mercury of Canada - Atlantic
A4 Mercury of Canada - Midwestern
A6 Mercury of Canada - Western
A7 Mercury of Canada - Pacific
B1 Ford of Canada - Central
B2 Ford of Canada - Eastern
B3 Ford of Canada - Atlantic
B4 Ford of Canada - Midwestern
B6 Ford of Canada - Western
B7 Ford of Canada - Pacific