I just recently replaced the fuel pump on my Mark III. I thought that would have solved my problems for a while. When I started the car a couple of days later it did not idle as smooth as before though. I checked everything and when I touched one of the ignition wires I got an electrical shock. So I knew that I would have to replace the ignition wires and ordered some new ones with spark plugs. When I entered the garage the next day there were some fuel fumes in the air which one could smell pretty clearly. The new fuel pump was dry and after a while of searching I saw that the carburetor was leaking fuel out of the accelerator pump gasket.
When I bought the car it already came with a Holley replacement carburetor which is very commonly used instead of the troublesome original Autolite carburetor. It does fit perfectly and you cant see this change from the outside at all.

So I had to order a rebuild kit from Holley. On this carburetor the accelerator pump diaphragm is very easy to replace. I just removed the carburetor from the car. You then have to remove 4 bolts to get the float bowl housing off and then 4 more screws for the accelerator pump.
I put new gaskets in, reinstalled the carburetor onto the car, put the new ignition wires on and wanted to install the new spark plugs I received. Unfortunately the ones I got from Rockauto did not fit. The Autolites they are selling have a 14mm thread which is way too small! They insist that they would fit on my car and did not want to take them back because of this. :-( Make sure not to order Autolite SP-459 for your Mark III - they wont fit!

Because of this I had to reuse my old spark plugs which still look very ok.
I put everything back together and fired the car up. It immediately ran perfectly again and idled like a Swiss watch.

The correct and the replacement Autolite SP-459 spark plugs which do not fit.

The carb still in place
The carburetor removed

The leaking diaphragm

New float bowl gasket in place

New diaphragm in place

Tags:1971, Lincoln Mark III Repair Tip, Lincoln, Carburetor, Autolite SP-459, Holley, Spark Plug Wire Routing, 1971 Lincoln Continental Mark III, Mark III, Rebuild