This summer I purchased a ’71 Mark III with 90,000 miles on it from the original owners. About seven years and 700 miles ago, they performed quite a few tune-up items, including points/condenser, plugs, wires, distributor cap and rotor, as well as other maintenance unrelated to my current issue including fuel filter, brakes, radiator, transmission and power steering flush service, carburetor rebuild, A/C and fuel pump . It has run well, but sometimes takes some cranking and pumping to get it to start if it sits for several days and seems to run a bit rich. It occasionally runs on after I shut if off; running the A/C all the time seems to put enough load on the engine to stop it.
I’m in the process of putting everything back to original, including a few items from Lincoln Land, cleaning up the engine compartment by installing a new battery and correct battery cables, correctly routing vacuum hoses, and replacing some that are in bad shape During the process, one of the plug wires came apart from the boot at the distributor cap. So, I proactively replaced all the plug wires, and replaced the cap an rotor with higher quality parts. When I reassembled everything, and routed the wiring, I also adjusted the path of the small coil wires to reduce tension on them. When I tried to start the engine, it turned but wouldn’t fire. So I fiddled with the yellow inline connector on the red wire between the coil terminal and wiring harness. It started right up and ran great. I noticed that yellow inline connector seemed to be all rubber, and could barely identify any copper inside of it. It doesn’t really snap into place, but seems to go all the way in a stays put. Later on, after a little more work, it wouldn’t start again. Then after a little fiddling with those coil wires, it started once. Now it won’t start at all with only an occasion attempt at firing. I tried adjusting those wires again, but no luck at all.
Does this sound like the coil took this opportunity to fail? And what about that wimpy-looking inline connector? I’m stuck having to tow the car to a mechanic if I can’t figure it out.
Also, regarding towing, what do I need to be aware of when towing this car?
Thanks for any advice.
Hi Bradley –
Your first paragraph lists several tune up items that were replaced or rebuilt on your engine according to the previous owners. You then describe starting difficulties as well as a ” run on” issue. From your description it sounds to me that the adjustments and operation of these components should be revisited at this time. This should include points adjustment and condition, carburetor choke operation and adjustment, fuel filter condition, fuel pump pressure and spark plug condition and adjustment. The engine ” run on” problems are many times proven to be caused by an engine that has too fast of an idle speed adjustment when at operating temperature.
In your second paragraph you describe an engine non start issue that is temporarily corrected by “fiddling” with certain wires. The problem returns shortly after and is again corrected by ” fiddling” with these same wires. If this is correct as you have stated then the wiring problem obviously needs to be identified and corrected. A visit to a good tune up technician however may be necessary. If you suspect that the coil may be failing I would advise substituting a good known coil as a test as diagnosing an intermittent coil operation would be difficult. New coils are usually not very expensive. As an another test a suggestion would be to bypass the coil mounted condenser and its wiring by connecting the coil feed wire directly to the coil. That coil mounted condenser is only used as a radio noise suppressor and could possibly be the problem as you describe. Proper diagnosis is critical in order to isolate and repair the faulty wire or component. A wiring diagram would be very helpful for you.
Following up on your advice below, I have good news. I got the car started, but it took a while to identify the problem. Because I could not get current to the coil, I researched replacing the resistance wire in my shop manuals. That involves running a new resistance wire between the ignition inside the car and the harness connector just outside the fire wall. But then I determined I was getting current to that harness connector on the engine side of the firewall, so I knew my problems was farther along the wire inside the engine compartment. It turns out that the little soft rubber yellow 90-degree connector in front of the carburetor that joins its red with green/grey-stripe wire from the wiring harness to the 3″ long red with blue/green-stripe coil wire was the culprit. I’ve attached a couple of pictures so you can see the connector I’m talking about. The soft rubber yellow male connector on the harness side is bad, and requires a very specific amount of pressure and position for the wiring inside of it to make contact so that current can reach its terminal. I have it positioned perfectly with a zip-tie so that it starts and runs, but obviously that is not a permanent solution.
Since it appears that this one connector broken, my question is this: Do you know if there is any current-adjusting operation taking place inside that little connector, or is it strictly a pass-through connector? If pass-through, I should be able to simply cut the connectors off, and replace them with a different kind. I’d prefer to keep the connectors original, but finding that specific type of connector is proving difficult. If that connector performs some electrical adjustment, I’ve got another challenge on my hands.
Good that you found the problem! That wiring connector that you are holding in your second photo is the one that I mentioned that can be eliminated as a test. These wire connectors do not regulate current, they are only means to splice in the radio noise suppressor condenser. If you would need another one along with the attached condenser and wiring we should have a good used one available. Contact George at our office and he will provide you with the details.