Ignition problem with my 72 Highboy

[thefordguy]

Hi, I've been having intermittent ignition problems with my 1972 Highboy - 360ci, 4spd, 2 barrel, all original. i think I have traced the source of the problem. The wire to the coil is receiving flashing voltage - and not 12v, closer to 9v or 10v. I pulled the plug/fitting that is near the firewall that has the 3 manifold wires - one is for the oil pressure, one is for the temperature sending unit, and the other is the coil. It looked to me that the 12v was going to the oil pressure gage, and the temp gage is receiving the same blinking voltage as the coil wire is receiving. I was careful to check that both the turning indicators were not flashing, and the hazzard flasher was not blinking.

I had noticed that at night the electrical system (headlights, dash lights) distinctly blinked like a flasher and thought it was a voltage regulator problem - so I replaced the voltage regulator and it seemed that the flashing had gone away. Now I realize that the flashing hasn't gone away.

Has anyone heard of this issue before? I appreciate your insight on this.

[fordman]

onback of the instrument cluste ris a ipvr. instrument panel voltage regulator. it sends out flahses of power to the gauges or senders. but it shouldnt be hooked to the coil. the coil recieves its power at start up from the igintion switch and the solenoid on the fender. if you dotn have a full 12 votls when you cranck the engine over. then you arent getting 12 full volts from the solenoid.

[thefordguy]

It would appear that someone the wires got switched. But I don't see how it could happen, unless the wires melted together somewhere. I did replace the gage cluster, but I recall having this problem with my old cluster too. I'm sure I can splice in new wires to correct this problem, but I'm trying to keep things original if I can.

[thefordguy]

I just realized that I must have swapped the coil wire and the temperature gage wire. I feel stupid.

[thefordguy]

ok, now I feel a little better. I just went to the car to switch the wires. But before I reattached the temp wire and coil wire I checked their voltage - this time the temperature wire was flashing, and the coil wire is 12v. and the car started up great. wtf! what could cause this?

[fordman]

that is correct. you have no problems. the temp wire is suppose to flash. so is the fuel and the oil wires.

[Thunderfoot]

The coil wire will/should have 6-9 volts on it with the key in the RUN position, but is should be constant (not flashing) then this wire at the coil will/should have 12V on it when the motor is starting with the starter running only, this is to help with starting.
If you seen that the coil wire was flashing at all, then you have a problem with the coil wire from the ignition switch, either the wire has an intermittent short in it or the wire is breaking down and needs replaced, or it could even be your ignition switch is getting worn out and making bad contact in it.



The gauge wires (Oil, Temp, Gas) should have a pulsing 5V on them as Fordman was talking about.