Help with Ford 3930...no crank

[TractorTech]

I don't think that the solenoid is bad. It started the tractor. Solenoids are either good or bad, no in between. I'm assuming that when you used the 8 gauge wire, you robbed power from the large lug on the end of the starter. If the solenoid has two spades, one is positive input and the other goes to ground. Placing a wire across the two spades would create a short circuit if the positive terminal is powered because the only load would be the resistance of the 8 gauge wire. Touching a hot wire to the negative side of the solenoid would also create a short circuit. You have a problem with the wire or with something in-line on that wire that is reducing voltage or blocking it. As I said earlier, the easiest and first place to check for me is always the ground cable. It is a quick check that probably fixes at least half of the no start issues on equipment that doesn't get used daily.

Not true. The lugs on the solenoid are the + lug bringing power from the battery. The other lug goes to the starter. When energized, the mass pulls in and completes the circuit within the solenoid between + and the motor. The solenoid also throws the bendix into the ring gear simultaneously. The shorting across the lugs may get the bendix to engage in the ring gear, but doesn’t rule out the solenoid.

 

[blehmann]

 

[blehmann]

I finally found a wiring diagram. I stand corrected. The starter is an enertia style that spins the bendix into the ring gear. The solenoid does not pull the bendix into engagement. So the next test that I would do is to disconnect the big wire off of the starter motor, put a test lead between the wire and ground, turn the key to crank and read the voltage. If none, then move the test leads to the smaller set of wires on the relay and ground to check if voltage is making it to the control side of the relay in the cranking position. If there is voltage, then change the meter to ohms and check between the control spades for continuity, with the wires removed. If there is continuity, you will know that the points in the relay are bad. If no continuity, you will know that the coil is bad. Either of these results, replace the relay. If no voltage is coming to the relay control side, then back upstream looking for an interlock that is open or perhaps a wire broken.

 

[Jason280]

I spent the better part of an hour trying to troubleshoot the starter solenoid (while in place), which is about as inaccessible as possible. Finally accepted that no matter what I did, I would have to remove the starter...which meant removing the filter assembly. Again. If there is one thing I have gotten good at, its removing/bleeding the filter housings. Pulled the starter, found that the back side starter bolt was completely loose. I doubt it backed out on its own, more than likely the last person to mess with the starter gave up on trying to tighten it. Its a pain to get to, required two different 1/4" extensions (one was a wobble), a deep 9/16" socket, and flex head ratchet...and still wasn't easy.

Before pulling the starter, I attempted a few times to get the solenoid to "close" by applying 12v power...never could get it to do anything. Same results with it on the bench, still nothing with 12v applied. I pulled the cap off the starter solenoid, not knowing a single thing what I was doing, and nothing looked obviously wrong. I cleaned up all the internal connectors, reassembled, and it started "clicking" closed with voltage. Not sure exactly what I did, nothing was really that dirty/tarnished/corroded, but I reinstalled and it immediately cranked over with the key.

Tractor is running great now, no apparent issues with the fuel or starter....let's just see if it stays that way!