Dash,
I empathize with you on trying to crawl around in the engine compartment as we get older. Here is a recap my understanding of the issues.
New to you older boat. It did run post some initial work. Now it will turn over and not start but will sputter like its trying to run.
The following had been done:
- Replaced Starter, Alternator, Cap, Rotor (not points as it’s an electronic module), wires, plugs, oil & filter, impeller. Cleaned out the carb and used fresh gas out of a can (eliminating possibility of bad gas in the tank).
- Testing has been: 12VDC at coil; spark at plugs based on using a timing light on each plug wire; Compression test good at 140-150#.
- Between was running and now not, it rained and only had a tarp covering engine, possibly got wet.
Let’s go back to basics. As you know three things are needed to run: Fuel, Spark and Compression. Compression is not in doubt per your test. But I suspect the other two may be an issue despite the checks done.
Here are my troubleshooting suggestions to be followed in the order presented.
- Disconnect the fuel from the carb and with that disconnected end placed in a bottle, crank over the engine and ensure getting good flow. If good flow, next step.
- With fuel line reconnected, the spark arrestor removed (so you can look down the carb) and the coil high tension wire grounded out (the wire that goes to the distributor so you do not get spark) have a friend crank the engine while you are looking down the carb with a flashlight. You should not see any gas flowing into the carb. If no gas flowing, next step.
- With the above set up still in place, and you looking down the carb with the flashlight, have your friend advance the throttle from idle to wide open. No cranking, only moving throttle. You should see a squirt of gas from the accelerator pump. If it squirts, next step.
The above is to validate fuel.
- Take the coil high tension wire and hold the end a few millimeters away from a good ground, like the engine block. Now have that friend try to start (crank) the engine. You should see sparks rapidly and strong. If good strong sparks, next step.
- Replace the coil wire and remove all the spark plug wires (do not want it to start). Using a spare plug or screwdriver, create the situation so you can observe a spark from that wire. Now have that friend try to start (crank) the engine. You should see sparks in time with the compression stroke (so not as many as before) but still strong. If good strong sparks, next step.
- Pull all the plugs out. Inspect them for fouling or extreme wetness. Validate the gap is correct. If all good, reinstall and next step.
- Reinstall the plug wires being carful the proper firing order is being followed > in other words the correct wire on the correct plug. If any doubt about this, do internet search.
The above is to validate spark.
Once all reassembled, try to start.
Post results of above testing and questions. Good luck!
