Starter will not disengage with engine running

I have 2 starters I have been testing with. A factory one, and a PMGR one. Both stay engaged after cranking, even with the key off and out, also the engine continues to run. I replaced the fender mounted solenoid with a new Motorcraft one, then replaced the ignition switch with a Borg Warner one. When the starter is stuck, I can pull the wire from the S terminal and it will disengage the PMGR starter, and the engine will continue to run. Pulling the S terminal with the factory starter will disengage the starter, but the engine also dies. Is it possible for the neutral safety switch to cause this kind of behavior?

 

Disconnecting connection from S terminal means one thing, wire has power when it's not suppose to be hot(and that's only in start position)... Not likely a neutral safety problem, something is shorted, crossed, miswired, etc, etc... Ign is back fed from I terminal while cranking, assuming ign at on position, engine should continue to run when S terminal is disconnected...

Is ign sw correctly set?? If it's mis-adjusted starter can continue to crank...

 

I had a similar issue and it was the starter solenoid.

Just because it is NEW doesn't mean it is not the problem.

 

I double checked the ignition switch yesterday to verify it was properly set. The S terminal wire is getting 5 - 6 volts with the key in the on position and a full 12v in the start position. I will attempt to isolate and test the wire today starting at the switch.

 

Have you done any work to the wires that connect to the solenoid? How many wire going to the small terminals and are there two small studs? It sure sounds like the ignition lead that gives a full 12 volts to the coil at startup might be on the same terminal as the wire that energizes the solenoid.

 

If both wires are on the same terminal power will back feed through the system to the switch as you describe. Since there is a resistor in the path from the ignition switch to the coil you will have reduced voltage as you are seeing. Your car should have points (originally) so the wiring should look like this, unfortunately I didn't find a diagram with wire colors.

 

Thanks guys, got it sorted out. Just in case anyone else ever encounters this, here is my setup. You are right Rick, originally it was a points ignition system. However, I put in a Duraspark system out of a 75, harness and all. On the 72, the S terminal wire goes straight back to the ignition switch. On the 75 it goes from the ignition switch to the Duraspark module, which then has a wire out from the module to the S terminal. A couple of years back, I replaced the original Duraspark module as I was having ignition problems, turned out it was the coil, so I kept the original module as a spare. After probing around with the voltmeter, everything off the ignition switch looked fine, so for the heck of it I plugged in the original Duraspark module. From that point forward, the S terminal wire began to behave as it should. I then switched back to the other module, and the problem returned. So now it looks like everything is working as it should, but I no longer have a spare Duraspark module.

 

Isn't electricity fun? Glad yu got it sorted, thise little gremlins can sure be frustrating!

 

This is probably posted in the wrong place, hope you bear with me for a quick question. My 73 mav 250 has, to my limited experience, a strange symptom...When attempting to crank, I get a click, whirr, or nada. If I take the brush cover off and press slightly on the spring loaded gear drive, fires right up..starter is a compilation of several ford starters...thanks, Rick, gonna send you a cordless ext. cord for your savvy....

 

That's not unusual really but I'm not sure what causes it. If it was GM it would be the starter mounted solenoid but fords are different. Could be a bad bendix but that might cost more than a replacement starter.

 

good man, Rick...thanks...

 

Usually that's the arm setting a little too high, magnetic field of armature can't pull it in place to extend gear. Try different arm/actuator, possibly shim where it rests on case. Also be sure contact is operating properly, its closed when disengaged, opens(activating motor) when arm extends gear. When fully engaged, contact should have .100 gap, max. A dirty contact will cause erratic operation.

 

Thank you for the timely response Tom...

 

I'm from back in day when starter, generator, & later alternator repair was common. Learned from my dad that had to fix his own or walk. Sixty years ago a replacement starter was around $25-$30, or more than a day's wages. A new drive & set of brushes for $6-$8 was mighty attractive. Watched him use a growler to check armatures for shorts & cutter to true worn/rough commentators.

I remember my uncle commenting these starters were lousy when introduced(worked at dealership). Said they'd commonly tear up the drive and often teeth on flywheel. At 13/14 years old I didn't have a clue, but a few years later learned if contact has too much gap, the motor will run before drive is fully engaged. Apparently no one at dealership garage read the shop manual.

 

There were still a few local rebuilders when I started in auto parts in 87. Never had to take a Ford starter apart, they always worked on the cars I had. The GM stuff was a different story, flipped the disc on many solenoids and turned over the contacts to get more life out of them.