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j_ramsey, ASE Certified Technician
Category: Ford
Satisfied Customers: 972
Experience:  ASE certified engine repair a/c steering suspension automatic trans
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1972 F250: Ford truck..Camper..390 and auto trans..coil

Customer Question

My Ford truck is a 1972 F250 Camper Special with 390 and auto trans. About 3 years ago, I installed a Pertronix Ignitor II and Pertronix Flame Thrower coil. All has worked well. A week ago, the truck would not start. Fired once, would not run. I checked Pertronix Igniter unit and it was burned. I replaced both the Pertronix Igniter and installed a new Pertronix coil. Truck will not fire. I checked high tension wire between coil and distributor and no fire. Suspecting low voltage, I jumped directly between the battery and the positive side of the Pertronix Igniter. Nothing! Can anyone diagnose what the problem is.
Submitted: 9 years ago.
Category: Ford
Expert:  j_ramsey replied 9 years ago.
Do a simple test at the wires to the coil, First check and make sure you have power at the (+) terminal of the coil ( using a test light) . Now check for a ground pulse at the coil (-) terminal when the engine is turning over. You just reverse the test light with the clamp hooked to the battery positive when checking the coil for a ground pulse. If you have power at the coil (+) and a ground pulse at the coil(-) then the coil is bad.
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Customer: replied 9 years ago.
Thank you for the prompt answer. To ensure I understand:
1. To test for power to the coil, I connect a light tester to the + side of the coil and with ignition on, go to ground. Light should come on.
2. To test for ground pulse, I connect the light tester to the battery + post, touch the - side of the coil, while turning the engine over. If I have a light here, along with a light from the check to the + side of the coil, I have a bad coil. Somehow, I think I have misunderstood your explanation. Given that the coil is brand new, what other problems could likely be the cause?
Expert:  j_ramsey replied 9 years ago.
You have it correct on how to check for power and ground pulse. I missed the part about replacing the coil, could you still check to see which of those that might be missing. Lets see if it is getting those to the coil,Im wondering if it may be missing the power.
Customer: replied 9 years ago.
Since it is 10:00 PM in Virginia, I can't do this until tomorrow, but do want to Accept so that you are paid for your work. If you would be so kind, if there is no power to the coil, what problem should I look for? In my initial explanation I mentioned that I jumped power directly from the battery to the + side of the Pertronix Igniter, which connects to the + side of the coil. Truck would not start when I performed this procedure. Likewise, if I get a light when performing the ground pulse test, what problem should I look for? Again, many thanks.
Expert:  j_ramsey replied 9 years ago.
Just a minute, I'm looking up the exact diagram for your system.
Expert:  j_ramsey replied 9 years ago.

I would first make sure I had power to the coil and on the corresponding wire of the igniter. Is yours with the resistor or without ? graphic

Expert:  j_ramsey replied 9 years ago.
If there is power to the coil + and the igniter and no ground pulse at the coil - then the likely problem will be the pick up coil in the bottom of the distributor.
Customer: replied 9 years ago.
OK, thank you.
Expert:  j_ramsey replied 9 years ago.
Let me know what you find out tomorrow.
Customer: replied 9 years ago.
Reply to j_ramsey's Post: Mr. Ramsey...Ran both tests this morning after recharging the battery overnight to ensure strong voltage. There is power to the + side of the coil and the test light flickers when grounded while the engine is turned over. I am on my way to buy a remanufactured distributor ($39.95)unless you advise otherwise. I am not skilled at working on distributors and its cold as dickens here. Thanks again for all your help...Customer
Expert:  j_ramsey replied 9 years ago.
If you have power and the ground pulse at the coil - terminal then there should be spark from the coil if it is new. If you have both then the coil should be firing, is it possible that the coil wire from the coil to distributor cap is bad? Or the Rotor is burned in the center and shorting the spark to the distributor shaft ?
Customer: replied 9 years ago.
Initially I replaced the coil wire without success. When I examined the rotor, it was black on the tip. I cleaned it and the distributor terminals inside the cap. What you say makes sense so I cam going to go back and look more closely at the rotor and distributor cap. Again, many thanks for your interest and assistance. BTW, we are now living in Virginia, but hail from Fair Oaks Ranch, TX, which is west of San Antonio. Oh, to be able to get back!!
Expert:  j_ramsey replied 9 years ago.
I can't imagine living somewhere colder,it felt like summertime here today in the high 70's. If the rotor had burned in the center then that would explain why the igniter was damaged.
Customer: replied 9 years ago.
Don't tell me that about the weather in Texas. I miss Texas so much. Actually, between wind and temperature today, I couldn't work on the truck. Our plan was always to return to the San Antonio area, but the real estate market has hosed our plans probably for several years to come.
Expert:  j_ramsey replied 9 years ago.
I can't stand it when we get into the 30's here(very rarely), I couldn't deal with anywhere colder.
Customer: replied 9 years ago.
Mr. Ramsey...I finally got the truck running. I replaced the distributor with a remanufactured unit, new cap and rotor. The distributor came with a set of point and condensor. I left those in. Hit the ignition and she fired immediately. I am sending the Pertronix Igniter back to Pertronix for examination and refund. I suspect that the new unit burned out immediately for some reason, but they are not supposed to do that. According to Pertronix, they are protected from high voltage. Anyway, the problem is solved, but the mystery remains. Just thought you might like to know. Again, thanks for all your help...Customer, Centreville, Virginia
Expert:  j_ramsey replied 9 years ago.
Glad to hear that you're up and running again. James