Homelite 7-19 weak spark, will not fire - Cars & Trucks

The coil makes the spark. If it's weak the coil's secondary winding is bad. Replace the coil.

By "fire," I assume you may mean SPARK. If the spark is weak, replace the coil pack.

Weak spark could be bad coil(s) or ignition module. Even a bad groud strap can cause this, but most common is module.

You are correct in your understanding. If the coil has at least 12 volts and gets a ground signal from the computer, the coil should fire. The coil actually sparks when the ground is removed.
The cam and crank sensors tell the computer when the cylinders are at top dead center which also opens the injectors.
Have you checked to see if you have battery voltage at the coil, and tried another coil ?

Did you change the leads?

The spark gets power to spark from coil packs.If the connection between coil pack to spark plug is weak or loose then it will not fire.But if the coil pack as well as the connection between coil pack to spark plugs checked ok then its faulty or dirty spark plugs.Clean the spark plugs with the carb cleaner liquid and let it completely dry.Then check.Also check the voltage between coil pack to spark plugs.If both checked out ok then the other possibility can be weak crank shaft sensor. Thanks.Helpmech.

I don't have enough info to give you a specific answer so I've listed a bunch of possible problem that could cause your engine to roll over but not start.
Check the battery and connections, a weak battery or bad connections can cause a weak spark and stop the engine from firing.
Fuel pump or fuel filter, low gas pressure can cause to lean of a air/fuel mixture for the engine to start.
Bad gas, old gas or water in the gas can stop the engine from firing.
Bad or fouled spark plugs, could be caused by bad gas.
Ignition wiring problems, can cause weak or unreliable spark.
Bad, poorly connected or misconnected spark plug wires. Even 2 wire out of order can stop the engine from firing.
Oily spark plug wires, can cause the spark to fire at the wrong cylinder or misfire.
Worn, damaged or wet ignition components.

A yellow spark is usually a sign of a weak coil, change that, it should cure the problem, if not, then further testing is needed.

id be leaning twords a coil pack on this one, if the spark is weak change the plugs and wires first since its cheaper, then if that doesnt cure it change the coil pack.

problem like this on garden tractor ,was weak coil ,-when engine at low manifold pressure[idle] spark could jump gap and fire cylinder ,higher pressure /under load-wouldn't fire...check color of spark -orange,yellow ,white spark=weak, blue spark is stronge,