Electrical 1990 Vert starting/Solenoid issues

Could be the ignition switch or you just got a bad start solenoid from the auto parts store. What brand did you get?

To test the start solenoid remove the 4 ga wire going to the starter off the start solenoid. Get a test light or DVM. Use the key and “start” the engine so turn the lock cylinder to the start position and then let it return to the run position. Now use the test light or DVM and see if the post that goes to the starter still has 12V on it after the ignition switch was released from crank but still in the run position. If it does check the small post that has the red wire with a blue stripe and see if it has 12V on it. If it does then my guess would be ignition switch. If not then it’s a bad solenoid.

I am not 100% sure all this will work with the starter wire disconnected as it may not load the solenoid enough to keep the contact closed.

However, if the red with blue stripe wire has 12V on it the whole time then I would definitely replace the ignition switch.

Could just be bad out of the box but the ignition switches are known to literally fall apart. If you need an ignition switch look for the Standard brand locally as the Motorcraft are way too high and the Standard units are as good. I’ve had one in my car for years now.

Rockauto also has these switches and if you search for the Rockauto discount code (sticky thread here) could get one even cheaper. Both the Standard and Motocraft switch is like $25-ish, plus a small discount with the code.

Fyi (and as @gkomo mentioned)....



And if you end up going with the Standard Motor Products one, make sure it's their US98 model and not their US98T model. (The T model one is their economy version.)