***RESOLVED*** replaced dead battery, now engine doesn't turn over.
The starter is turning the engine and the engine fan. It's not firing and "turning over" to the engine to run on it's own.
Please use correct terms. "Turning over" and "cranking" is the same thing, meaning, "the engine is rotating with the starter."
It's not FIRING is what you mean to say
Next job, then is to check the spark.
You need to understand the difference between
1.....Cranking the engine by twisting the key
2.....Cranking the engine by jumpering the starter solenoid
That is important when checking spark, because if you jumper the starter solenoid, you can mask some problems and wrongly assume you have others. The coil power "in start" comes from a special contact on the IGN switch called the bypass or IGN2. This is brown, it is only hot "in start" and it only goes one place-----from a contact on the IGN switch to the coil + side of the coil resistor.
The "ignition run" (IGN 1) line goes DEAD in start
So you need to ............
"rig" a spark gap checker to the coil tower, so you can see it through the hood gap, or 2 people. Twist the key and look. You should get a nice blue snappy rythmic spark, at least 3/8" long.
DO NOT use the factory coil wire for this test........it is probably resistive, it might be open, and so on
If that test seems OK pull one or two plugs and see how they look.......Dry? Wet? fouled??? "Rig" them with the wires to ground, and again try the key. Crank the engine long enough to "be sure," and look for spark at the plugs.
If this is OK, you have "the basics"
Which is
COMPRESSION..........enough compression in the cylinders to run, probably at least 75PSI. Consider a compression or leak-down test
SPARK. Good hot spark and at the right time. Maybe the timing chain slipped. You can check timing by cranking on the starter with a light
FUEL. Good, fresh gasoline. Maybe a helpful neighbor kid filled you up with water / other. maybe you got ahold of a diesel nozzle. Hey, it happens
If the plugs are dry or don't look fouled, consider a shot of starting fluid, or about a tablespoon of known good fuel down the carb