1990 Ford F150, 4.9 I6 ignition issues. Key will turn over and the fuel pump will send the fuel but no crank over

Question

Had an issue before changing the ignition switch, any tapping above the ignition lock cylinder on the steering column caused the truck to shut off. We have changed the ignition lock cylinder, and the ignition switch and for certain we have the rod and the switch set in the right way. but now there is no cranking over

Outside in the engine bay, there is a place on the fender where you could touch the starter wire and an ignition cable (?) and it would turn over if you had the key turned over and ready to crank

maybe there might be another issue with something electrical in the steering column? i see a purple/black wire with a contact to the ignition lock cylinder...

Answer 1

I dont know if they had anti theft device in 1990 (I dont think they had) but if it does you probably need to send it to the dealer.

Now I think you may have a electrical issue. Getting information. Wiring diagrams and connector pin out is a good start.

First thing to look at is fuses. You may have burnt one without realising when replacing the switch. Go check that out

Then unplug the switch (remove it if its easy to do so) and test the switch with a ohmeter (on a multimeter) make sure the contact is made between the pins b+ and start. (I know its a new one but dont assume its ok)

If the switch test ok and no fuses is blown take out that diagram and diagnose. You may take a look at the starter relay. Switching it out with another known good relay is a fast and easy test.

And remember when doing electrical diagnosis. NEVER ASSUME a wire/connector/component is ok. TEST IT.

Answer 2

Is it possible the switch slid down the shaft? The bolt holes on that switch are tapered. On the same truck I've had an issue where I changed that switch, than 6 months later the bolts backed off a tiny bit and the switch slid down 1/4 inch, so the rod wasn't able to go far enough and allow it to crank over.

Answer 3

Inspect the end of the ignition switch connector..

Make sure that none of the terminals have burned or backed out of the connector body..

Did you put a new ignition switch on the side of the column.. ?? like this: https://bit.ly/2TCphD3 look at picture 2.. see the slot where the control wire goes in.. you can push the switch in one direction and look inside at the contacts .. see if they are burned on one edge.. meaning that somebody put a old switch back in the box and returned it to the store.

lets do a test.. do you have a test light.. unplug the S terminal on the starter solenoid so you are not cranking the engine.. find the coil positive connector.. it will have a second short pigtail to the external capacitor.. stick the probe in the positive side.. ground the test clip.. slowly turn the key from the locked position thru run.. thru cranking .. slowly back to run... then slowly back to locked.. you should have constant power with no flickering from Run, thru cranking and back thru run till you get to the off position before you get to locked..

Another test. turn the key to the On position.. the test light is still hooked up in the coil positive... have a friend watch the test light. while you tug on the ignition switch pigtail.. i had one decades ago. .that the pigtail was not snapped fully into place.. it would die when drove the pickup up a steep hill.. drove the owner crazy.. drove the dealer crazy. they finally called me and i found the connector not snapped in fully..

You can see that the pigtails come out of the ignition switch connector really easily: https://bit.ly/3giiI2c

This is a quick test.. probably less than 10 minutes.