Ignition troubles
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Ignition troubles
Hello all, I am new on here and hoping to find a answer. I have a 1969 f250 camper special with a 390. It had a miss in it and I replaced the coil but the miss was still prevalent. I had heard about the resistor wire and replaced it as well. When I replaced it my voltage at the coil was 8 volts running. The truck ran fine for awhile, I noticed that my , lights flickered so I replaced my alt, voltage regulator, coil, and points and condenser. Now when my truck runs I have 8 volts at an idle but when it is off idle or accelerating I get up to 11 almost 12 volts. This is a problem, I have since again replaced alt, and voltage regulator stillmdoes the same thing. I unhooked the voltage regulator, and the alt and my voltage at the coil still increases with rpm and I still have a miss now off idle and idling, anyone got an idea? I am stumped!
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I only have a miss underload, I just wired the truck up with a ballast type resistor off a dodge and the engine ran great. I had 7.5 volts at the battery side of the coil. Hooked it up the factory way. I have 8.56 volts to the battery side of the coil and when you pull the choke out and rpm increases to 2000 rpm i have almost 12 volts to the positive side of the coil. Voltage regulator is new and so is altenator.
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I only have a miss underload, I just wired the truck up with a ballast type resistor off a dodge and the engine ran great. I had 7.5 volts at the battery side of the coil. Hooked it up the factory way. I have 8.56 volts to the battery side of the coil and when you pull the choke out and rpm increases to 2000 rpm i have almost 12 volts to the positive side of the coil. Voltage regulator is new and so is altenator.
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Compression on cylinders is fine and I can pull every plug wire off the cap or off the plugs and the miss does not go away. The miss ONLY goes away when I have a ballast type resistor hooked to the battery then to the coil, then my truck runs perfectly on idle and off idle.
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From: Butler, IN
I think you are on the right track. With what did you replace the resistor wire? Most don't replace the wire but put a ballast resistor in place of the offending wire. Voltage at the coils should only be 7-9 volts. 12 volts at the coil and the points will burn thru in less than a year or 10,000 miles.......whichever comes first!
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I did a replacement according to what I read in my ford book. It states to cut the resistor wire and splice in the new one and tape it along the old wiring harness. I did just this. But I am beyond stumped. I just ran the engine with the alt, voltage regulator, and both sides of the starter relay (s,i) unplugged and my voltage still creeps up and engine wants to break up off idle. Timing is within spec and vacuum is very good. I just dont get it, i can run the hot wire set up with a ballast type resistor and the truck runs fine. But why wont it work the way its suppose to. I did notice tonight that where the resistor wire splits inside the cab from the resistor wire to the starter relay had voltage that creeped up too. But it did not do this at the ignition or at the starter side of the relay.
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From: Butler, IN
I think you know the answer. Remove the resistor wire and put in the ballast resistor as it has shown it runs the best with it. I think the ignition system is getting feedback somewhere from an unknown source. If the resistor wire was working properly, it wouldn't let 12 volts thru. That is how a resistor works, it restricts the voltage and won't let any more voltage thru than what it was designed to, even if the engine RPM was increased.
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Right I would like to have it the right way, but it doesnt seem to work. And I am puzzled as to where its getting feedback through, possibly the ignition switch? or a bad ground, perhaps even the dist?
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From: Butler, IN
After I have slept on it, we may be closer to result. I think you wired in the resistor wire correctly, so that can be ruled out. When a Ford truck is cranked, 12 volts is sent directly to the coil to help start the engine. The coil gets 12 volts from the solenoid at this time from the ignition switch. Look at the this diagram: http://www.fordification.com/tech/wi...9charging2.jpg
#32 wire from the ignition energizes the solenoid to send 12 volts to the starter motor and 12 volts to the coil via #262 wire. This rules out the ignition switch as the starter motor stops when you put the switch in "run" position. To check the ignition switch, after the truck starts, test for power from #32 wire. It should be 0 volts. The same should be for #262 wire. To check the solenoid, run a jumper from the negative side of the battery to the grounding plate of the solenoid. This is to check that it is properly grounded. If there is power at the #262 wire with the grounding wire attached, good ground......bad solenoid. Let me know if this solves your problem. There may be a direct short in the #262 wire if the wires have have rubbed together but that will take some time to sort out.
#32 wire from the ignition energizes the solenoid to send 12 volts to the starter motor and 12 volts to the coil via #262 wire. This rules out the ignition switch as the starter motor stops when you put the switch in "run" position. To check the ignition switch, after the truck starts, test for power from #32 wire. It should be 0 volts. The same should be for #262 wire. To check the solenoid, run a jumper from the negative side of the battery to the grounding plate of the solenoid. This is to check that it is properly grounded. If there is power at the #262 wire with the grounding wire attached, good ground......bad solenoid. Let me know if this solves your problem. There may be a direct short in the #262 wire if the wires have have rubbed together but that will take some time to sort out.
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Thank you all very much, I checked the grounds and the truck seemed to run better, I checked that wiring diagram and the one for a 68 since my truck came down the assembly line in 68 I noticed a small ground wire going from the alt, to the engine in addition to the number 26 wire which goes to the volt regulator. However, I am about to graduate college so back to school for me I will post later with what it is. Thank you all again.
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Update: After graduating I am back home, I checked all grounds cleaned all grounds and I now have 9 to 10 volts at the coil with no more spikes. So looks like it was the ground. Thank you all very much!
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If you have not checked the engine to chassis ground you might want to. Goes from firerwall to engine, most likely still original. Behind carb more towards drivers side.
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