My son and I tried to get our 74 F100 started today (first time in 10 years). Everything clicks when the key is engaged- starter will not spin at all. I checked and there does not seem to be power on the starter side of the solenoid when I turn the key. I replaced the solenoid- same thing.
When I jump the positive side of the battery to the starter side of the solenoid, the starter spins? Do I need a starter, I am at my wits end?

Also how long after turning the engine over should fuel pressure be at the carb (again after it has not started in 10 years)?

 

Make sure under the solenoid is rust free!!!! Wire brush the mounting area and the back of the solenoid. Check your cables!! Form the solenoid to the starter and also the ground cable. The solenoid mount is the ground for the solenoid, and if that does't have a good ground it will either do nothing or just click.

 

I will check that, would that limit power getting to the starter side of the solenoid? I checked the battery ground as well and that seemed to be ok.

 

Just re read the post. There is no ground on the starter, one positive wire only, I thought the starter grounded itself on the block?

 

The starter grounds by bolting to the transmission bellhousing, which is bolted to the block.

So, you're observing the following:

1) Solenoid clicks when key turned to START.
2) Starter does not spin with key in START and solenoid supposedly engaged.
3) No voltage on starter-side of solenoid.
4) Starter spins when forced on.

When you checked for voltage on the starter-side of the solenoid, did you make sure it was still engaged? About the only way to do this is with a helper, unless you jump the solenoid.

 

I never said there was a ground wire on the starter. I just suggested to check the ground cable from the battery to the engine block. Because if you can jump the solenoid and the starter cranks then it's either the solenoid or wires. The solenoid mounts on the inner fender well. Yes?

 

I had another run at it today still no luck. Changed the positive and negative cabled and checked ground. Sanded behind the solenoid as suggested, no change.
I did check the voltage one of the small wires coming to the solenoid (I think it is the ignition wire?) and it only show 6 volts. Should it be 12 volts?

 

Yes we checked it with the ignition on, the rest you have written above is exactly whats going on.

 

The ignition on as in RUN, or the ignition on as in the key held in START? If you simply turn the key on (RUN) then walk around yourself to the solenoid, you won't see anything on the starter side of the solenoid. The START position of the ignition switch is momentary.

Your comment about the "I" terminal is why I'm asking you to clarify. You will see 6 volts at the "I" terminal of the solenoid if the key is in RUN. With the key in START, you will see the same voltage at all 4 terminals of the starter solenoid.

If you turn the key to START and the solenoid clicks, yet you have NO voltage at the starter-side of the solenoid (which means the starter will not turn either), then the new solenoid has to be bad out of the box - the fact that you get a click means you're getting power to the 'S' terminal and the solenoid is properly grounded. Once that happens, its only job is to pass current from one large lug to the other through a large plate inside. However, please clarify the position of the key when you're looking for voltage at the starter side. The only valid way to check this is with a friend holding the key in START briefly while you check. You can also check this yourself by fixing your multimeter to the starter side of the solenoid with alligator clips and jumping the 'S' post of the solenoid yourself.

 

I was turning the key to Start and a mechanic friend was checking the voltage which was 6 volts, he could not understand it either? I should mention the truck has the factory dual battery system with two solenoids. I am starting to wonder if the main solenoid is clicking or I am just hearing/feeling the auxiliary one resonating through the system.

 

Yes - a second solenoid in the system would have been helpful to know from the start.

The reason you are seeing 6 volts at the "I" terminal of the solenoid is because it sounds like the key is in RUN even though it's being placed in START - possibly due to a bad ignition switch. The "I" terminal of the solenoid is tied to the positive terminal of the "I"gnition coil. When the key is turned to RUN, the voltage at the coil is split between the ballast resistor in the wiring harness, and the resistance of the primary winding of the coil - so you see 12 volts divided by 2, or 6 volts.

Let's do this very easy test: hold the key in START again, and have your friend check the voltage at both small terminals of the starter solenoid. First make sure you see 6 volts at the "I" terminal to make sure you're back where you started. Then pull the wire off the "S" terminal and check the voltage at the wire end - I bet you won't see anything. If I'm right, then your ignition switch isn't actually getting power out to the solenoid, and the click you're hearing is probably the other solenoid.

 

I will check tomorrow and let you know. When you refer to the ignition switch I assume you mean the key switch in the cab ( probably a stupid question)? Thanks.

 

You got it - the ignition switch is engaged by the lock/tumbler cylinder. And no such thing as a stupid question.

If the test I've described checks out, there are a couple other things to check first before blaming the ignition switch. This is just a start.

 

Alright, round 3, I replaced the ignition switch with a new motorcraft piece- no luck. I checked the aux solenoid, grounded it and still nothing. Last resort I jumped in and moved the gear shifter back and forth and it would turn over periodically. I tried that before and it did not work, but it works now so I am happy! Anyone know how to change a neutral safety switch?

 

It's attached to the steering column by the floor. Unbolt and unplug and do the opposite with the new one