The explosions on low and the petarders are due to ignition failures, the pick up, it had been warning of a ignition failure when doing this you comment.
When he didn't want to start and the spark plugs soaked in gasoline came out, it was because the ignition finished breaking and the spark plugs ran out of spark.
The first thing is to remove the spark plugs from the butt and with them outside, turn the engine with the start to see if there is high voltage current.
If there is no current and depending on how the ignition is (since I do not have the technical details of that engine) it will be time to look at coil or ignition coils, crankshaft position or camshaft sensors if it carries them, contact current in coil and in ignition module, distributor's draft ... etc.
All the best.