My 1986 E-150 300 cu. in. inline six just quit while driving about forty mph. There is no
spark to the plugs. This engine has the TFI ignition module mounted on the distributor.
What I checked so far: 1. I replaced the TFI module with a working spare but still no
spark. 2. The cam timing gear is ok, as the valve lifters work when rotating the
crankshaft. 3. The distributor shaft turns with rotation of the crankshaft, and the rotary
vane cup and Hall effect unit are intact. 4. The ignition coil resistance readings are
within spec, and there is 12 volts going to the + terminal of the coil. 5. I haven't found
any obviously broken or dangling wiring. So, any ideas about what else to look for or
check? Thanks for your help guys.

 

If you have a test light available to use, try this.
With the key on and have someone crank the engine over while you touch the test light to the other end of the coli primary connection. Remember one terminal of the coil is hot when the key is on , the other end should also cause the test light it glow until you crank the engine, then it should blink indicating the pick up coil in the dist is responding to the dist shaft turning. If you get this, the coil should produce a spark.
It would also be a good idea to confirm that the rotor is pointing to the correct terminal (#1plug wire) inside the dist cap with the crank pulley lined up with the TDC
mark at the crank pulley pointer. Let us know if you at least have this much taking place.

 

Here are the results of the test suggested by Hanky:

With a test light on the negative side of the ignition coil (low voltage contact), the light glows when the ignition key is turned to the run position. When the ignition key is turned to the start position and the engine is cranking, the test light continues to glow steadily. Just to be sure, I also connected the test light to the other (+) terminal of the ignition coil and observed the same result; the light glows steadily with cranking. So it seems that the ignition coil is not firing because it is not being connected to ground by the distributor/TFI module. Would I damage the ignition coil or electrical circuitry if, as a test, I independently connected the ignition coil to a ground, and then lifted the ground wire to check for a spark in the high voltage wiring?

What's next in testing this system? Thanks for your help Hanky

I have not yet confirmed that the distributor is correctly positioned, but assume it has not moved. The hold-down nut is tight.

 

There is a pick up coil in the dist that sends the signal to the ign module to let it know the dist is turning. Sometimes the gear on the bottom of the dist will shear the rolled pin that holds it to the dist shaft. If the rotor is not pointing in the right place at TDC that pin could have broken. Also, the pick up coil in the dist could be open and not forwarding the signal to the module. The pick up coil can be checked with an ohmmeter for continuity and if open will have to be replaced. The dist will need to be removed to do this if required. The quickest thing to do if possible is to have the module tested at any auto supply store that will run the test for you. Then if that test is OK you may need to go after the pick up coil itself.

 

With regard to the distributor shaft gear being stripped, when I removed the distributor cover I attempted to rotate the shaft by hand, and it seemed solidly firm. Cranking the motor caused the distributor shaft to turn, suggesting that the gear pin is not sheared. But if it was sheared and the rotor was off TDC, wouldn't it still generate a spark from the ignition coil, even though not at the proper firing position, assuming nothing else was amiss?

I also checked the resistance of the Hall Effect sensor in the distributor. There are three wires to this sensor, red, green and black. I can't determine the exact orientation of these wires, but in testing with an ohm meter, there is infinite resistance between two pairs, meaning they are open, and the third pair indicates about 10,000 ohms in one direction, and infinite ohms (open) when I reverse the meter polarity. These wires connect to the three exposed contacts on the TFI module that mounts to the distributor base.
Assuming that a Hall Effect sensor is a semiconductor, the measurement of 10,000 ohms in one direction and infinite resistance in the other direction suggests that the sensor may be functioning properly. Not sure about the fact that the two other wire pairs are showing an open circuit condition.

Are there other tests that I can perform on the Hall Effect sensor to further check it's condition? And what else might have failed in this ignition system? Thanks to hanky, and others who can offer any help.

 

Before condemning the hall effect switch in the dist make sure the wiring and connections are good from the dist to the module and module to the ECA and coil.. With the key on supplying power to the red wire if you crank the engine over you should get a digital signal that you can measure between the green and black wire. If that is not present you may have a defective hall effect sw assy.

 

It was a long hard winter in Buffalo New York, and I left the van sitting until last week to avoid freezing to death while working on it. The solution to my problem was to replace the failed Hall effect sensor in the distributor. Although the Ford shop manual says that the distributor sensor is not serviceable, my garage mechanic told me that he has replaced many of these sensors. All that is required is pulling the drive gear off the lower shaft and lifting the shaft out of the distributor housing. Then the sensor is easily replaced. The sensor cost $20. Many thanks to Hanky for all his help and suggestions.

Mark

 

I haven't looked to close the reply's be for me but just for quick check mine has a shut off switch on the right side of the inside of the van by the passenger leg its to shut things off if you hit something it will sometimes shut off if you hit a really pot hole .just saying

 

Good point,
I believe it is called an inertia switch.
It's job is to interrupt power to the fuel pump in the tank in the event of an accident/mishap. It can be tripped if the vehicle is bumped when parked so kind keep that in mind if you parked the vehicle in a lot and when returning it won't start. To reset it all you need to do is depress the button. You can actually feel it when it is being reset, just about all Fords today still use it!
Different models have it located in different places on the vehicle, good to know it's location, check with owner's manual.