1981 Ford Bronco no spark

Tiny
81FSB
  • MEMBER
  • 1981 FORD BRONCO
  • V8
  • 4WD
  • AUTOMATIC
  • 200,000 MILES
Itz a cali emissioned 302

1. I can not locate the ballast resistor.
2. I am getting no spark out of the coil. I have replaced the coil, the ignition control modual twice, the crank postiioning sensor the distro cap and the rotor. I have also traced both the positive and negative off the coil and do have continuity through them both
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Thursday, March 12th, 2009 AT 11:15 AM

11 Replies

Tiny
RACEFAN966
  • EXPERT
Ok this is an 81 Bronco there is no crank sensor or ballast. Now I figure you are refering to the pick up coil in the distributor itself. Now I also need to know if you have a digital multi meter? I would like to know if at the + side of the coil do you have power with the key on engine off? If so do you have power at the neg side of the coil if so how many volts? Get back to me with that first and then I will look at a wiring diagram and see what wires I need you to test as this could be the ignition switch too but lets do some tests first and make sure. Get back to me with what you find ok.
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Friday, March 13th, 2009 AT 11:13 AM
Tiny
81FSB
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Ok I might have a different motor(possibly newer) cuz I have replaced the sensor located next to the harmonic balancer the distributor does not have any wires coming out of it. Yes I do have a multimeter and yes I get about 6.5 out of the + side of the coil. I have also tested continuity for both wires coming off the coil to the end of the wires that I can trace.
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Friday, March 13th, 2009 AT 2:19 PM
Tiny
RACEFAN966
  • EXPERT
Ok I think I know what you have you have a california model Bronco. So it has a crank trigger not a sensor because there is just a hollowfect distributor that is non adjustable for timing and the carb should be a veriable venture carb as well. The venture carb has black sliders on the top it is not like a normal carb. If you have a newer motor it would injection and have a computer and such. So if you would please take off the air cleaner and include a pic of the carb and such. I really need this info to better help you as this system is on its own and different from any other system and it was only used on caliifornia smog vehicle with ford and not very popular either. This is the best pic I can up with. Let me know so we can do this right ok.


http://www.2carpros.com/forum/automotive_pictures/249564_getimage_1.jpg

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+1
Friday, March 13th, 2009 AT 8:53 PM
Tiny
81FSB
  • MEMBER
[quote="racefan966"]Ok I think I know what you have you have a california model Bronco. So it has a crank trigger not a sensor because there is just a hollowfect distributor that is non adjustable for timing and the carb should be a veriable venture carb as well. The venture carb has black sliders on the top it is not like a normal carb. If you have a newer motor it would injection and have a computer and such. So if you would please take off the air cleaner and include a pic of the carb and such. I really need this info to better help you as this system is on its own and different from any other system and it was only used on caliifornia smog vehicle with ford and not very popular either. This is the best pic I can up with. Let me know so we can do this right ok.

lol yes this emissions set up is not very popular and is going to get removed on the accout the i dont have emissions here in this part of ohio. i dont believe that is the carb that is on i have several pictures for you to maybe help. if this one does not help i can post others


http://www.2carpros.com/forum/automotive_pictures/330503_DSC03485_1.jpg

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Sunday, March 15th, 2009 AT 2:39 PM
Tiny
RACEFAN966
  • EXPERT
Ok so I need you to get a digital multi meter and check the voltage at the possitive side of the coil and then the voltage from the neg side of coil. You will need to do this with key on engine off. If you do not have voltage to the possitive side of the coil then go to the starter solenoid and if there is a wire hooked to the I side of it then hook up your meter there and see if there is any power there with key on engine off and then crank it and see if there is voltage there. If you would include a pic of that sensor on the crank and one of the distributor without the cap on it. Also the module what color is the plastic where the wires go into it. Let me know what you find ok.
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Monday, March 16th, 2009 AT 12:08 PM
Tiny
81FSB
  • MEMBER
I apologize for the length of time before a response

Battery at 12.39 v dc
postitive side of coil key on engine off 7.30
negative side of coil key on engine off 2.54

the plastic grommet is brown with five wires. i believe the ignition system is the duraspark III


http://www.2carpros.com/forum/automotive_pictures/330503_DSC03502_1.jpg

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Friday, March 20th, 2009 AT 5:21 PM
Tiny
81FSB
  • MEMBER


http://www.2carpros.com/forum/automotive_pictures/330503_DSC03503_1.jpg

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Friday, March 20th, 2009 AT 6:25 PM
Tiny
RACEFAN966
  • EXPERT
OK lets check the coil wire what is resistance of it is should be less then 5000 per inch of wire.
Now lets do a voltage supply test to the ignition system ok. First you need to check the starter relay if there is a I term then I need you to disconnect the battery cable between the relay and the starter. If there is no I term on the starter relay then disconnect the wire on the S term. Now at the ignition module I need you to stick the white and red wire with a straight pin.
Now turn the ignition switch on and check the voltage at the red wire it should be near battery voltage.
Now have someone turn the ignition to start possition (like you are going to start it but it will not try to start) check for voltage at the white wire it should be battery voltage.
Now have someone turn the ignition switch to the start possition again and check the voltage at the possitive side of the coil it should be near battery voltage.
Now go ahead and turn the key off and disconnect the voltmeter and remove the pins and hook you starter relay wire back up. If the voltages where less then 8 volts at any point then check the wires going to the ignition switch if all it ok there then replace the ignition switch. Here is a pic of how to hook things up if you need it. The next 2 pics are for reference later if needed.


http://www.2carpros.com/forum/automotive_pictures/249564_Graphic2_8.jpg



Do you have a box like this anywhere?


http://www.2carpros.com/forum/automotive_pictures/249564_Graphic1_5.jpg



Here is a pic of the wiring for the ignition system. We may need this later.


http://www.2carpros.com/forum/automotive_pictures/249564_Graphic_52.jpg

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Saturday, March 21st, 2009 AT 9:20 AM
Tiny
81FSB
  • MEMBER
[quote="racefan966"]OK lets check the coil wire what is resistance of it is should be less then 5000 per inch of wire.
Now lets do a voltage supply test to the ignition system ok. First you need to check the starter relay if there is a I term then I need you to disconnect the battery cable between the relay and the starter. If there is no I term on the starter relay then disconnect the wire on the S term. Now at the ignition module I need you to stick the white and red wire with a straight pin.
Now turn the ignition switch on and check the voltage at the red wire it should be near battery voltage.
Now have someone turn the ignition to start possition (like you are going to start it but it will not try to start) check for voltage at the white wire it should be battery voltage.
Now have someone turn the ignition switch to the start possition again and check the voltage at the possitive side of the coil it should be near battery voltage.
Now go ahead and turn the key off and disconnect the voltmeter and remove the pins and hook you starter relay wire back up. If the voltages where less then 8 volts at any point then check the wires going to the ignition switch if all it ok there then replace the ignition switch. Here is a pic of how to hook things up if you need it. The next 2 pics are for reference later if needed.

Do you have a box like this anywhere?

Here is a pic of the wiring for the ignition system. We may need this later.

Ok with the key on the Red wire has 11.75, roughly what the battery is. The white wire ( key in the start position) only gets 1 (one) volt. The coil (key in start position) gets 7.5 volts. So from what you are saying my issue will be between the modual and the ign switch, or possibly the switch its self? If I am correct the box your looking at would be the main computer. Located under the drivers seat? If so then yes
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Saturday, March 21st, 2009 AT 10:06 AM
Tiny
RACEFAN966
  • EXPERT
Ok that white wire is the problem this is why it won't start. It needs to be 12 volts too or close to. So check the wire for any breaks if there is no breaks in the wire then yes the ignition switch is bad, as this will be the reason the white wire is not getting its full voltage. You would need to replace the electical part of the switch not the key and tumbler part ok. See the coil recieves full battery voltage on start up and with out it, it won't start. As for the computer under the seat yes that is what I was asking about we will get to that if needed. Get back to me with what you find.
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Saturday, March 21st, 2009 AT 7:43 PM
Tiny
81FSB
  • MEMBER
Alright sorry about the delay. So after installing and reinstalling three different ignition switches I am left with the old switch that will turn over the motor and power everything else (i.E radio). And a new switch that will not turn over the motor but does provide power to everything else. I have check continuity with all the wires off of it and they all are in working order.
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Monday, April 6th, 2009 AT 9:59 PM

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