I'll start out with my main question: how many volts should be a the wire that runs to the starter selonid?

My 84 is having a problem starting and the starter is clicking, engaging with the flywheel but not turning the engine, and I am afraid it is a wiring issue. I checked that wire while the key is in the start position and I have 12.5 volts at the battery, and only 7.5 volts at that wire at the starter.

I checked the wiring at the clutch start switch. If i disconnect the switch, the yellow wire(supply) has the same volts as the battery when the key is turned to start. Now when I ground out the clutch switch or hook it up to the switch, I am getting 10 volts on the supply wire and the outgoing wire.

I cant find the starter interupt relay, so I cant test that.

Now is the 7.5 volts at the starter feed wire ok or too low? If too low, where the hell am I losing power to that extent?

This is giving me headache...

 

BTW, the main battery cable to the starter is at the proper volts and matches what the battery is putting out.

 

Should be 12V

 

When you hit the start position, you apply battery volts to the starter solenoid on the starter. When the starter solenoid engages the starter pinion gear into the flywheel ring gear, it also connects the large battery cable to the starter motor and the starter should crank the engine. The starter draws 100+ amps when cranking and the battery terminal voltage during cranking must not fall below 9.0 volts or the battery is discharged, battery cables are making poor connection the battery terminals, or the battery is at the end of its life. First remove the battery cables (neg first) and clean the cable lugs and the battery terminals until they are clean and bright and reconnect (neg last). Next, charge the battery overnight with a battery charger. You can tell the state of chare of a car battery by measuring its terminal voltage after it has sat unused for 24 hours. 12.0 volts and below, discharged, 12.9 volts and above, fully charged. If you see a large voltage drop (more than 3 volts) from the battery + terminal to the starter during cranking, then you have either a poor cable connection to the battery, poor ground from battery - to the frame, or you have a bad connection in the large wire of the battery cable to one or both of the lugs that connect to the battery.

 

For clarification, the main battery cable is ok. On that terminal on the starter I am getting the 12.5ish volts. The one I was refering to as getting 7.5 volts is the small ppl wire that goes to the smaller terminal. I think that is the wire that sends the signal to the starter seliniod to turn the starter.

 

When cranking it has 12.5V? If not, then the voltage means nothing. If the terminals are corroded, cable is internally defective or the like, you'll get 12V, but at that point the impedance is so high that it can't support the starter's current draw.
The purple wire should have 12V on it, that is the wire that energizes the solenoid, if it drops below 9V the solenoid will disengage.

 

While cranking itsdown to about 11.7 or so on the gague. But when not cranking it jumps back up to about 12.5.

The thing is, if it flick the key a few times (5-6) it will turn the starter as normal. Im wondering also if I could have a bad ground on the engine

 

You are correct and that wire should not see only 7.5 volts. You have some resistance in that circuit causing a voltage drop. It could be in the ignition switch, the start enable relay contacts, the clutch safety switch, or in the firewall connector. You can find where by putting a hefty load (auto headlight, or several stop lamps) on the purple wire at the starter and measuring the drop across the ignition switch, relay contacts, the clutch safety switch (gear selector sw if automatic) and the firewall connector. Good luck.
Oh yeah, there is a fusible link to the ignition switch and you might have to measure the voltage drop across it too. I would expect to not see more than 0.2 volts drop across any of the parts above with a 5-10 amp load at the starter purple wire!

If you can hit the ign sw a few times and get the starter to crank, you probably have a worn starter solenoid switch contacts which get pitted and eventually have too much contact resistance to to supply the starter motor with enough current to crank the engine, ...BUT... you should see 12 v on the purple wire when attempting a crank.

 

That helps a lot. The ingnition and clutch start switch are both new about a year ago.

the thing that confused me is I disconnected the clutch start switch and measured the yellow wire(from the ign switch). When disconnected, there was 12.5 volts on that wire. I tried bypassing the switch and jumping the connector. On the yellow wire it dropped to 10.25 volts. When I disconnected the jumper wire, the yellow supply wire jumped back up to 12.5 volts.

Im thinking I got a wiring issue some where but not sure where to start

 

Start tracing that wire backwards.

 

Current to the clutch safety switch comes from the battery through a fusible link, through the firewall connector, through the ignition switch, through the start enable relay contacts. These are what you are going to have to measure to find out which one has the resistance that causes a drop in the voltage at the clutch switch. Jump the clutch switch and have someone hit, "crank" momentarily while you measure across the battery, then across the fusible link, then across the ignition switch, then across the start enable relay contacts. If you don't measure anything more than about 0.2 volts, then measure across the negative battery terminal to the frame to ensure that you don't have a resistance connection to the frame on the negative battery cable.