My F250 is a carbureted 87 with a mechanical fuel pump, just to get that out of the way......


Long story short, truck was puttering along one day and caught on fire. A lot of stuff melted. I bought a used distributor, carburetor, and intake manifold, a new coil, cap and rotor, new plug wires, and spark plugs.


I also bought a Ford shop mechanics electric schematics on the real big paper 3 page fold out so I could reconnect the wires that burned to a crisp.


I connected the wires best as I could but the heat from the fire did make some things hard like red with yellow stripe looks an awful lot like purple with a white stripe etc.


I put my meter on the coil terminals + and - with the key on it showed 6 volts. Since Im doing this by myself and don't have a remote starter switch I put the test light across the coil +/- and cranked it over. It didn't flash it just stayed on but it got real bright when I cranked it compared to when the key was in the run position.


Any help would be greatly appreciated. I tried to do a search on here, but the web said there was trouble with the site. I hope this gets through, thanks

 

Don't go across the coil, go from the coil +to ground, and go from the coil - to ground. Coil + to ground you will get around 9v, higher when cranking. From the - to ground you will get blinking when cranking. If you don't get blinking on the - of the coil to ground, you have a problem with the ignition module not turning the coil on and off. I would check power to it.

 

Thanks Dave. I forgot how that worked it's been so long since I worked on a car with an oil canister coil.
The fire didn't get anywhere near the ignition box on the fender skirt so I hope that's not it.
I'm leery about all this because I bought an old holley to replace the melted one that came stock. It had all kinds of wires going to it and I'm not going to hook all those things up. If I don't hook up the carb bowl vent solenoid it wouldn't stop the truck from getting spark would it?

 

No, it will run without all that other stuff hooked up.

 

Awesome! Is there a test that can be done on the distributor to see if the pickup is good? Like using an ohm meter somehow?
Since I bought a used distributor Im suspicious about it and would like to test it to see if it's good before I bang my head against the wall trying to chase down shorts or other electrical craziness.

 

Here's some test you can do. I am assuming you have the duraspark II system with the large square box on the inner fender.

To test the stator (also known as the magnetic pickup assembly), you will need an ohmmeter. Run the engine until it reaches operating temperature, then turn the ignition switch to the off position. Disconnect the wire harness from the distributor. Connect the ohmmeter between the orange and purple wires. Resistance should be 400-800-. Next, connect the ohmmeter between the black wire and a good ground on the engine. Operate the vacuum advance either by hand or with an external vacuum source. Resistance should be 0-. Finally, connect the ohmmeter between the orange wire and ground, and then purple wire and ground. Resistance should be over 70,000- in both cases. If any of your ohmmeter readings differ from the above specifications, then the stator is defective and must be replaced as a unit.

If the stator is good, then either the electronic module or the wiring connections must be checked next. Because of its complicated electronic nature, the module itself cannot be checked, except by substitution. If you have access to a module which you know to be good, then perform a substitution test at this time. If this cures the problem, then the original module is faulty and must be replaced. If it does not cure the problem or if you cannot locate a known good module, then disconnect the two wiring harnesses from the module, and, using a voltmeter, check the following circuits.

Make no tests at the module side of the connectors.

1. Starting circuit: Connect the voltmeter leads to ground and to the corresponding female socket of the white male lead from the module (you will need a jumper wire with a blade end). Crank the engine over. The voltage should be between 8 and 12 volts.


2. Running circuit: Turn the ignition switch to the ON position. Connect the voltmeter leads to ground and the corresponding female socket of the red male lead from the module. Voltage should be battery voltage plus or minus 0.1 volts.


3. Coil circuit: Leave the ignition switch ON . Connect the voltmeter leads to ground and to the corresponding female socket of the green male lead from the module. Voltage should be battery voltage plus or minus 0.1 volts.




If any of the preceding readings are incorrect, inspect and repair any loose, broken, frayed or dirty connections. If this doesn't solve the problem, perform a battery source test.
Battery Source Test

To make this test, do not disconnect the coil.

Connect the voltmeter leads to the BAT terminal at the coil and a good ground. Connect a jumper wire from the DEC terminal at the coil to a good ground. Make sure all lights and accessories are off. Turn the ignition to the ON position. Check the voltage. If the voltage is below 4.9 volts (11 volts for Dura Spark I), then check the primary wiring for broken strands, cracked or frayed wires, or loose or dirty terminals. Repair or replace any defects. If, however, the voltage is above 7.9 volts (14 volts for Dura Spark I), then you have a problem in the resistance wiring and it must be replaced.

It should be noted here that if you do have a problem in your electronic ignition system, most of the time it will be a case of loose, dirty or frayed wires. The electronic module, being completely solid state, is not ordinarily subject to failure. It is possible for the unit to fail, of course, but as a general rule, the source of an ignition system probably will be somewhere else in the circuit.


IGNITION COIL TEST


The ignition coil must be diagnosed separately from the rest of the ignition system.

1. Primary resistance is measured between the two primary (low voltage) coil terminals, with the coil connector disconnected and the ignition switch off. Primary resistance should be 0.3-1.0-.


2. On Dura Spark ignitions, the secondary resistance is measured between the BATT and high voltage (secondary) terminals of the ignition coil with the ignition off, and the wiring from the coil disconnected. Secondary resistance must be 8,000-11,500-.


3. If resistance tests are okay, but the coil is still suspected, test the coil on a coil tester by following the test equipment manufacturer's instructions for a standard coil. If the reading differs from the original test, check for a defective harness.

 

Excellent assistance and well written.

 

I copied and used paste from Autozone's repair section.

 

Knowledgeable and honest, too! Good attributes.