1979 Mark V Hard To Start When Cold

Hi Bill,
I Have a 79 Mark V Collector’s Series, 20K miles with a mystery problem I am at a dead on. When engine is cold it takes up to 50 pumps to get started. 3 years ago it took 10 to 20. Once started it runs perfect in every way and restarts when warm with a half pump.
Car has new plugs, wires, cap, rotor, gas and air filter. Linkage seems tight and normal, butterfly closes as it should on first pump. A good spray of carb cleaner into the carb helps it to start easier.
Logically it seems like gas in draining back and all the pumps are bringing fuel back to the carb but several people tell me this is impossible. Most parts on this car are original
Once it starts choke seems normal. Slightly higher idle for a few minutes, then normal
No gas odor, no exhaust smoke. No sign of flooding.
You can see why I need your detective work….
Thank you Bill,
Charlie
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Hello Charlie –
Some of these cold start problems can be frustrating but sometimes the answer turns out to be simple. An engine requires a strong battery, starter motor, good ignition and a fresh clean fuel mixture to start. When cold the engine also needs a richer mixture. Assuming that your ignition is in good order as you are indicating I think that you should examine the fuel system first. The choke on a cold engine start should be fully closed even while cranking. When the engine starts the choke opens slightly and continues to slowly open completely as the engine warms up. Fuel in the carburetor should be available in abundance at this time for the correct mixture. You tell us that the addition of carb. cleaner helps it to start easier. For this reason I think that you should hold the choke open on the cold engine and carefully observe the inside of the carb. with a light while pumping the linkage. This is of course is done with the ignition key OFF for the purpose of checking the fuel availability to the cold engine from the carb. If the ignition is strong and plenty of fuel is pumped into the carburetor at this time and the choke is operating as described above the engine will start. If fuel is not pumping into the carb. during this test you have a fuel delivery problem to the carb. or the accellerator pump inside the carb. is faulty. You would then need to check for a plugged fuel filter at the carb. and then perform a fuel pressure and volume test. This is outlined in the manual and will reveal if there are any problems for the fuel to be able to flow correctly from the tank to the carburetor. Fuel cannot drain back from the carb. and into the lines as the vehicle sits unused but if the car has sat for a long period of time the fuel can evaporate and deteriorate. In this case a few seconds of cranking will replenish the fuel bowl if the fuel delivery system is performing for you as designed. You may discover during the above tests that your problem is indeed a fuel delivery issue and that this ciircuit will need a complete inspection and maintenance. This service is normal for a vehicle of this age. I hope that the above provides you with “food for thought” and helps to quickly locate the starting problem with your MK V. If we can be of further help with any advice or parts etc. please do not hesitate to call.
Sincerely,
Bill