I was tried the search but nothing quite what I was looking for.
89 F250 with 5.0 engine. New plugs, wires, cap, rotor. Suddenly would not start. I have no spark and went to the coil. One side is two green wires that go down into the harness to a brown block that has a red/lt blue and purple coming into it. This side of the coil has no power. The other wire is a yellow or tan wire that has power constantly. Both of these are with the key on. When I turn the key I hear the fuel pump run for a second or two.
I know the ignition switch has some issues (sloppy, tough to get the key out) but it has been working. I beleive the double green should have power but I do not know how to trace it out. Any hints? If I put 12v to this will I fry anything? I am working outside and would like to move it inside if possible to work on it.
I'm not into the colors on these wires, but only one should have power to it. If you aren't getting spark through the spark plug wires when cranking the engine, the most likely thing to go bad on this vintage Fords is the ignition module on the side of the distributor. You can remove this module without pulling the distributor, but you need a special tool, available at many auto parts stores. Beings it has died and won't start(not intermittent) you can have the module tested. Many auto parts stores can do this.
I now have the dist. out. Any way to test the module at home? I called Pep Boys and they proved yet again why they are going out of business. They can not test the module...
If the tan/yellow is key on 12V then the green must be switched from the module. Since this is not going on/off when I crank the engine I guess the module is bad. I hate to just start replacing pieces.
Back at it - The coil should have 12V on one side and on/off on the other side making the spark. I know I have 12V on the tan/yellow side but the other side is dead when checking with a probe going to ground. Should the green side be going to ground to collapse the electrical field in the coil?
It seems to me the truck is not switching the coil on/off to make the spark. How can I trace this back to the TFI or some other broken connection?
If you have the distributor out, the best thing to do would be to take it to your local Ford garage, unless you know a good independent garage that has the proper test equipment. They can check to see if it's firing properly and replace the necessary part(s). I still think it's the ignition module on the side of the distributor, with this vintage(primarily '86-91) Ford it's not if the ignition module will fail, it's when the ignition module will fail. I wouldn't worry about the coil or the wires by it. I don't think there's a problem there. Your cheapest bet here yet would be to find that special tool to remove the module from the distributor(you still need the special tool even with the distributor removed from the vehicle) and find an auto parts store that tests them. Good luck.
The module checked properly but I replaced both the module and the pick up and I am running again.
The cool trick I learned was to touch wire H5 of the connector at the module to ground for a second. This jumps a spark at the coil. That let me feel good the coil and all wiring was good. I think I could have just replaced the module but the pick up was only $18 and after 198,000 was probably going to go next!