I might invest in a tester Gumby thanks for that idea.
Forgot to say that I looked at the starter connections and they seem like they are solidly connected.

 

That ground strap in the second to last picture looks pretty corroded at the bolt/eyelet. I would disconnect then battery, disconnect each end of the wire, then clean up the metal and bolt with a wire brush or sandpaper to ensure you have a good connection. You may want to clean other connectors that look to have corrosion.

Your other alternative is to try a voltage drop test on the wires when trying to crank the engine to see if you have excessive resistance in your wires.

 

I'll clean it up PA and see if that helps. Do you know where I can find a list/diagram of the other connectors like that in the engine bay? (Also just curious what that wire is for. I've never really noticed that wire before today and it looks like it just connects together two pieces of metal)

 

Is there anyway to test if the starter might be bad without a scope and taking it off?

 

That ground cable is there for redundancy - there are several of them between the engine and body/subframe to make sure there’s plenty of paths to ground should the primary engine ground cable be severed/compromised.

IMO it’s not worth cleaning up - you can replace it with a short length of 10 gauge insulated wire and new eyelets. There should be at least 2 other similar wires (ground straps as some call them) in the engine bay - check along the firewall and both fenders.

To test the starter without removing it - remove the starter relay and jumper the switch side of the relay (the relay should have a wiring diagram printed on the side - a standard ISO relay uses pins 30 & 87 for the switch). This will bypass all ignition related controls and engage the starter solenoid directly so the key doesn’t have to be on.

Don’t crank for more than 15 seconds and allow about 1 minute between crankings for the motor to cool.

EDIT: I apologize for the incorrect information but I just double checked the wiring diagram and the starter relay power feeds are both from the ignition switch, so the method I described will not work.

You’ll need to either disable the fuel pump to prevent starting or run a jumper wire directly to the starter solenoid ignition terminal to crank without the key.

 

Looking at the corrosion on that ground strap, it is safe to assume that other grounds may have that level of corrosion. The easiest way to find all the grounds is to get a shop manual for your car. You can get a pdf on automanualsource.com for ~$22 and the manual will save you money and time in the long run. The cheap way is to follow the wire harness and battery cables around your engine bay and clean them.

I would disconnect the battery, clean the battery posts and terminals, and clean all ends of both battery cables. Also clean any grounds that are easy to access.

If you want to test first, the starter is a simple circuit. The power to the starter is fed through the big red battery cable attached to the starter. The signal to the starter is the small blk/wht wire that gets a 12V signal from the ignition switch through the starter cut relay. Test the signal to the starter first, so unplug the blk/wht wire, connect a test light to the blk/wht wire on the harness connector and use a bolt on the starter body as the ground connection. Have an assistant try to start the engine and see if the test light turns on. If the test light doesn't turn on, then you will have to work backwards to figure out the electrical issue.

To verify the big red wire is working, I'd probably disconnect that wire from the starter (battery disconnected first), then use a jumper cable you would use to jump start your car, and connect one end to the starter post (be careful not to have that jumper touch any other bare metal nearby), then the other end to the + battery post. Try to start the car like you normally do, and see if that fixes the issue.

 

PA, Gumby thanks a ton. Really appreciate the info. Didn't realize that is what those wires were for Gumby.
The connection wasn't super corroded underneath but it was dirty. So I cleaned it. I will look for the other ones and clean them tomorrow. And then test the wires as you recommend PA
I have a pdf of the shop manual.
They give a procedure for testing if the starter is the problem, so I'll do that after the cleaning.

 

I cleaned all the other grounds I could find, including the main negative ground strap. Also ran the test described above. Starter engaged fine.
Started the car 3x without problem and then drove it. Started it again 3x without problem and drove it again.
Could it have been as simple as cleaning the grounds? Maybe yall will say welcome to electricity.
If you all think there's another test that it would be good to run, I'll run it as I'd prefer not to get stranded.
Appreciate everyone's help in resolving this.

 

I do hope this solved the problem for you, but I’d be hesitant to call it fixed just yet. It’s possible cleaning the grounds eliminated part of the problem, but you were concerned about a possible drain on the battery as well, so maybe see what happens after it sits a day or two.

 

Thanks Gumby, going to fire it up today.

Looking at the wire diagram the problem makes sense to me now. The most corroded connection (2) was the one that grounds the starter.