1978 Town Car Issues

Hi Bill,
The other day I barely made it into the driveway after a 25 mile trip with
my 1978 Continental Town Car 400 engine with 40k miles.
A new gas filter proved not to help. Since it had the original plugs, I replaced them and put on the second set of wires, and replaced the cap and rotor. No change. I have checked all vacuum lines and they prove OK. Today, I blew back the gas line
even though the gas was leaking out at the fuel pump when disconnected. I put
pressure on the line from the gas filter to the fuel pump and it was clear.
The fuel pump was replaced about 5k miles ago. The car was not easy to start so I turned up the idle. It runs smooth pretty much at high idle after about 5 minutes, but when putting it in gear, it goes down to a shake if warmed but will stall on choke.
Also I checked the gas cap by removing it and still no change. I have used carb cleaner on all vacuum lines going in and into the carburetor and the carb shows they are clear by increasing the idle. I have also used carb spray directly into the carb with no change. Am I missing something stupid or do I need the carb rebuild?
Thanks.
Ed
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Greetings Ed –
Sounds like you were lucky to make it back home. A car that had the original plugs and wires still in use after 32 years could also have the untouched original and never serviced carburetor on the engine. It could very well be and likely is that the carburetor is in need of a good cleaning after this amount of time and 40,000 miles even though it may not actually be your problem as described.
Since you have checked part of the fuel delivery system I think that you do need to continue and do a fuel pressure and volume test at the carburetor inlet. This will show that the pump is able to draw fuel from the tank through the screen in the tank through the fuel lines and then pump it to the carburetor. If this test proves ok and the fuel delivery is in good order I would move to the carburetor at this point. You can check to see if the choke is operating properly first. The choke must be closed upon starting a cold engine and then it must open slightly when started and then continue to open fully as the engine warms up. The carburetor inside could be gummed up or the floats and needle valves could be faulty and allowing the engine to flood with fuel (too rich a mixture). Of course other problems can develop inside a dirty carburetor as well. If you agree that the carburetor has never been cleaned, I think that it is overdue for this service.
Another problem that could cause this stalling on your 78 Lincoln is a failing ignition system. Your car has an excellent fully electronic ignition system. Electronic parts can and do fail and the problem may first appear as a stumbling or stalling condition. Some failures may cause the engine to shut off and not start until repaired. Your particular problem could of course possibly be the first scenario.
I would first approach the situation with a complete fuel system check as described above including a carburetor service. After that and if the problem persists I would then check the ignition system. A seasoned tune up mechanic may be able to pick out a problem quickly as he will actually see and hear the engine running. We hope that the above leads to a speedy repair for you and if there are any parts or advice that we can provide, please do not hesitate to contact us at Lincoln Land.
Sincerely,
Bill