1978 Continental 400 Cutting Out

Hi Bill –
I have a 1978 Lincoln Continental with a 400 that will start cold, run great for about 1-2 minutes and then cut out immediately. At that point, the engine has no spark. We have replaced the ignition control module, coil, EGR valve, PCV valve, pick up coil for the distributor, spark plugs, wires, cap rotor and are still having the same problem. The engine is getting fuel.
It has to be something simple at this point following all the parts replaced but we are out of ideas.
One thing we noticed is that the power seat clicks when the door opens on the car. We have heard of a secondary ignition switch, and wonder if the power seat relay may be interfering in some way and shorting things out but simply don’t know what to think at this point.
Any thoughts would be greatly appreciated.
Thanks,
Steve
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Greetings Steve –
As you are finding out some of these electrical issues sure can be a nuisance. If you are actually loosing ignition after 1-2 minutes as you have stated I would want to first determine if the fault is loss of electrical power to the electronic ignition components under the hood from the ignition switch or a further under hood wiring or electronic issue that you could have previously overlooked. To properly diagnose in this manner you will need the correct vehicle wiring diagram and a 12 volt test light. The wiring diagram will show you the correct wire and color under the hood to monitor with the test light for this test with the engine running. When the engine stops due to loss of spark (as you have stated) your test light will either go off or remain lit. If the light remains lit, the problem will be a further under hood fault. If the light goes off, the problem will be somewhere in the wiring towards the ignition switch, any junctions or the switch itself. In this case the wiring diagram can be used for further testing in order to pinpoint the fault. Always keep a lookout for possible wiring modifications by a previous owner. A shop manual would be needed to understand and further test the Duraspark components on the engine side.
I have no knowledge of an actual secondary ignition switch as such but on a two door coupe the click that you hear could be from the automatic seat back release solenoid as the door is opened in order to gain easy entry and exit to the rear seating area.
Sincerely,
Bill