4.0L OHV Crank No Start after Sitting & Overheating

[RangerJoey]

Hi All,
I have a 1999 Project on my hands with the 4.0 OHV engine. Currently, I'm at a crank-no-start and wondering if anyone has any insight on what my next step should be.

Just a quick background: This might not be your normal crank-no-start. About a couple of years ago, the truck was started and allowed to run in a closed(ish) enviroment while high-revving the engine. The result was steam everywhere and from what I can tell, the coolant overflow must have flipped open to relieve the pressure. But never stalled out or anything.
I recently picked up a new battery, (and tested it), poured a tiny bit of new fuel in there, (basically empty gas), and checked the coolant. The radiator was empty. I didn't drain it to verify and thought it just needed topping off, but it took like over a gallon of coolant to bring to the neck. No leaks anywhere as I poured.
I went ahead and tried starting it and nothing. It just won't turn over. I found this thread on another site. It relates to the 3.0, but a pretty good "driver's seat" checklist before moving to actual tests.
PATS: The PATS indicator does not blink rapidly when the key is on the "On" position
Check Engine Light: The CEL comes on with the key in the "On" Position but goes off when trying to start the motor

That seems like it rules out PATS and Crank Position Sensor. So from what I've ready online, it's either Fuel, Spark or Compression. I know the tank could have old gas and I also know the Fuel Filter was replaced since the Truck has been sitting. So I picked up a can of Starting Fluid. I sprayed directly into the Throttle Body while it was wide open. It seems like it's just about to turn over, but nothing. I'm spraying directly for about 2-3 seconds. I could give it more, but also saw some scary YT videos of backfire. I did try going about 5 seconds and it gets closer to turning over but I feel like I'm already giving more than I should need, (Walmart Super Tech brand btw)

So at this point, I'm still looking to figure out if it's A) Fuel or B) Spark / Compression. At what point do I rule out Fuel if this Starting Fluid doesn't help it turnover? Unfortunately, I don't have access to any compression tests or anything.

And a couple of important notes:
It's super hard for me to be certain with all the chimes in the truck, but I don't feel like I'm hearing the Fuel Pump prime. If the starting fluid turned it over, I'd suspect something going on with that, but nada.
When I checked the oil, it's not milky or anything at all like that. it does sit on the high side of the dipstick indicator at cold, but both oil and radiator cap show no signs of anything milky
In addition to the CEL behaving as you'd expect (noted above), there's also a "Check Gauge" light that behaves the same way. Is that a preboot thing or a flag of a problem?
And finally, the inertia switch seems to be fine and not tripped for what it's worth
Horn worked so I swapped the Fuel Pump Relay and Horn Relay. Still no start but the Horn still works after swapping

 

[franklin2]

First most important. You said "it just won't turn over". That means different things to different people. To me that means that the starter is not turning the engine. Is that true? All that other stuff doesn't matter if the engine is not spinning when you are turning the keyswitch all the way to start.

 

[RobWigglezz]

The check gage light is for low fuel.

When it's cranking over, is it slow? If it's not slow and cranking over at a normal rpm, does the rhythm sound even? Or is there a tone change for a second?.

The extended high rpm untill it got hot and built coolant pressure could have damaged a few cylinders and a compression test is the first thing I would do.

 

[RobWigglezz]

It getting super hot, spitting out a bunch of coolant, and then turned off could have gotten the rings in a few cylinders to loose their tension. When you test for compression, might as well see if a spark plug is sparking also.

 

[RangerJoey]

Thanks! And I'm 99% sure it didn't turn off during the heat, but I've only had one other instance of a car sending out steam and that was from a hose popping off and squirting onto an already hot engine. I don't know what sort of scenario could cause the overflow to pop open.

I don't want to discount the state of the engine, but it gets so close to turning over with that starting fluid. I sprayed for a solid 5 seconds into the throttle again, tossed the hose back on and it really wanted to turn over. I'm just nervous about putting too much in there. It's sort of a one-person task unfortunately so I can't just spray while trying to start.

And to confirm, the cranking really seems to sound normal. Not labored or changing tempo/frequency. As in you're expecting it to start other than it won't.

One question: regarding the fuel pump, I can't hear a thing. But again, one-person effort right now. I've read about banking on the tank while starting to crank and all that. But if I put a phone under the truck to record when I put the ignition to "on", would that sound of the pump priming really come through?

Oh - and thank you! I thought I read the "Check Gauge" was a gas thing but there's about midway from E to 1/4 tank according to the dash. I can bring it up at least a quarter of some fresh fuel. I also have something from Sta-Bil called "Start Your Engine!". I think it's something you spray directly in a tank. Not sure how effective it would be going down the filler neck as a mist though.

 

[Jazzer]

Yeah, if you put your phone on a bucket or something, on voice memo setting close to the fuel tank, you should hear the 2 second pump noise on key turn. Also check fuel pressure at fuel rail schrader valve.