i have a 1977 thunderbird and ive been having issues getting it to start. it turns over fine,
and im getting fuel to the carburetor. but it seems to have a mind of its own on when it
will start. some days it starts up no problem and other times i can drain the battery
completely and it wont start.
Does that 77 have a duraspark? is it still bolted to the inner fender with more than one screw? Do you have low spark or no spark ? You can try another duraspark or you can investigate the voltages in the primary circuit and the resistor wire. The public library may still have repair manuals that old by chilyon, motor, or mitchell. some reference libraries even had Ford books donated to them. Since it is almost 40 years old, any loss of the correct voltage in the circuit can be caused by the wires, the connections, or any component.
After those results are known you can investigate the switching if the primary and if you need new guts in one of the finely wired ignition parts, the tests in the book should lead you. be sure of your specs for inputs and your expected outputs. try to use motorcraft parts and you can enjoy another lifetime of joy and beauty in that ride.
The most common failure these is the ignition module and distributor pickup coil, try this: get it failure, unplug the ignition coil and put a test light on the positive wire to ground and turn on the key, you should get a steady light, if not it could be an ignition switch or wiring problem , if you geta light then put the test light in between the two connectors on the wires that connected to the coil, crank the engine and watch for a flashing light, if the light flashes replace the ignition coil, if the light does not flash replace the ignition module and distributor coil, I usually replace these as a set cause you never know when they were last replaced. HTH
i forgot to mention that once i have it running it tends to cut out and die within the first 5 minutes on the road then starts really hard and runs fine till i leave it parked over night
Nothing you just stated would change the testing I just stated on the ignition, but I would add in checking the carb, the choke could be malfunctioning, or the pull off going to far open, also check the hot air door, make sure it is operating, the carb could be icing up during the intial start up and drive.
Here is something I found, there may come a time when you may hit start and it turns over fine and starts but when the key returns to the run position, the engine shuts down, I found that if I slowly manually returned the key from the start position in the direction of run .... it will first disengage the start solidnoid, but when held at that point, the engine will continue to run just fine as long as the switch is held at that point, but when allowed to return to run...the engine stops. The ignition switch is defective, and is located behind the instrument cluster.... a real pain !
You can gain more access by dropping the steering column down, just remember to remove the shift indicator cable.
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