Engine Turns but won't start

Question

It's an old Renault 4-cylinder carburetor engine in a boat. I don't know much about engines so let me know if I'm not including important information.

The boat is old but new to me. I drove it for about 4 hours, but now it won't start.

When I press the ignition switch, it turns ("reverevrev" sound)., but the engine never starts.

• There is gas and yes I'm pumping it into the carb and yes I've verified that it's getting into the carb.
• It started failing to to start immediately after being run for 4hrs and then turned off. I checked the battery and it's about 12.6V (but gradually falling as I keep trying to start the damn thing).
• If I'm persistent and keep pressing the ignition, the engine stops turning when I press the ignition, and I just hear the starter motor going "whiiiir". If I leave it for a while and then try again, it turns again, so I assume something has to cool down.
• When the ignition's turned on (but starter is not being pressed), the coil (leading to the spark plugs) gets hot. I'm measuring ~11.2V on the coil when the ignition's on, and 12.2V on the battery. There's also about 0.6V across the wire connecting the coil's negative terminal to ground, which I guess means there's a lot of current flowing across that wire, which would explain the heat.
• I took out the spark plugs, they were really black, so I cleaned the contacts with sandpaper and put them back in. (One of them seemed to not be insulated perfectly - 20MOhm resistance over the gap - but I'm guessing this is not the source of my troubles). Anyhow, this didn't seem to affect anything, and it still fails just as much as before.

So I suspect that there's something off with the coil, but I don't know what to normally expect here.

Any help is appreciated, by me and all people who buy crappy boats in the future.

Answer 1

It's me, your future self.

So it turns out that you're an idiot and all you had to do was fiddle with the choke. That little lever on the carb? That's the choke. I forget which way is open and which way is closed, but if you do the following:

1. Push the ignition switch.
2. If it doesn't start, move the choke lever to the other (closed) position.
3. Push the ignition switch again. Engine should start.
4. Quickly put the choke back to the open position (or engine will die again)

The new starter motor you bought might not have been a total waste of money since the old one was spinning sometimes, but the new coil probably was.

PS. Don't try to go under that bridge in 2 months. It's too low.