My first boat — 1983 Commander 26

I would get new electric ignition distributors for both. I know points keep things simple but there's enough stuff to mess with on a boat to worry about points. I saw one of those pertonix units on a Landcruiser many years ago but don't know much about them
 
How old is your coil, good shape appearance wise? Any signs of a crack in the plastic? Try swapping between motors.
I have had the small condenser fail but it killed all spark.
The Petronius generally work or do not work. Issue is something else I would say
 
Appreciate everyone’s comments on the spark problem. I’ve swapped the condensers between engines, which didn’t change anything. And checked primary and secondary coil windings resistance, which are correct and the same on both engines. (I also checked for continuity on both coil wires. They were both the same also, but I had no idea that coil wires had such high resistance. An interesting tidbit of new knowledge for me.)

I’m getting a new Pertronics. If it doesn’t solve the problem, I’ll have it on board as a spare.
 
Installed the new Pertronics, gapped it. Engine ran fine.

The punch line: I didn’t know the gap could be adjusted on Pertronics ignition until I read the install directions on the new one. Never tried. Didn’t realize there was any play in the mounting to adjust. So then I put the two igniters I already had back in, gapped them, and they worked fine! 🙄 Oh well, a learning experience.
 
Can anyone help with an apparent flooding at idle problem?

Ongoing saga. So, I had it out for sea trial number three. Finally, both engines are running fine, and I had fun zipping around on the plane. For about 20 minutes.

Port engine was overheating so I shut it down and came back on the starboard. I’ve been on the dock since. When I started the port engine to investigate the overheating problem, it wouldn’t idle.

It starts easily if I give it quite a lot of throttle, and sounds fine above 2000 RPM. When I ease the throttle back to 1800 or less, the rpm goes up and down a couple of times, then stalls.

Recent history: The two 180’s are new to my boat, so I don’t have an operating history, but I trust the marine mechanic who was maintaining them in the boat they just came out of and said they were in good running condition. I’ve only had the boat out for three sea trials. The port engine started easily and idled well for all three trials, But had very low power on the first two trials. I replaced the pertronix ignition and it had good power and ran fine initially on trial number three but started overheating so I shut it down and returned on stbd engine.

Since then, it won’t idle, as described above. Seems like it’s flooding at low throttle. I swapped the Rochester Quadrajet carb with the Quadrajet carb off a 488 (very similar but not identical; it was working fine on the 488). That didn’t change anything. Still sounds fine above 2000 rpm, surges and stalls if reduce throttle to 1800 rpm. So I’m thinking the problem isn’t in the carb itself.

All the tests have been at dock, in neutral.

My online reading suggests the (only?) other cause or to be high fuel pressure. But I haven’t touched the fuel pump since the engine was idling fine on the first two sea trials, and at the start of the third. Nevertheless, I guess my next step is to get a fuel pressure gauge.

I don’t think the engine overheated to a critical level on the third sea trial. And I also don’t see how overheating could have lead to the stalling at idle problem.

Help, please!
 
one suggestion - did you accidentally knock out the vacuum line/pcv valve. Often a wonky low speed idle can be traced to the PCV. Typically both valve covers will have a vacuum line back to the intake, but only one will have a PCV. Very easy to knock it loose.

Since it was running, and you were working on it - triple check that you didn't knock something loose.
 
one suggestion - did you accidentally knock out the vacuum line/pcv valve. Often a wonky low speed idle can be traced to the PCV. Typically both valve covers will have a vacuum line back to the intake, but only one will have a PCV. .
Thanks I’ll try that now.
 
Its a truism of life that at least half of our problems are self-inflicted;)

Also, if you were playing with spark plugs, re-check your that the wires are connected to the right cylinder. Anything else like that - super easy to mess something up
 
I don’t see a pcb valve. Just a hose from valve cover to flame arrester. It was disconnected much of the time I was testing (flame arrestor was removed), but when it was connected, it made no difference.
I did some more reading. Looks like 180 never had a flame arrestor fitted. It’s a 1987 inline four, 3.7 litre. And I’ve never seen one on my other four 3.7’s.
 
I don’t see a pcb valve. Just a hose from valve cover to flame arrester. It was disconnected much of the time I was testing (flame arrestor was removed), but when it was connected, it made no difference.
I did some more reading. Looks like 180 never had a flame arrestor fitted. It’s a 1987 inline four, 3.7 litre. And I’ve never seen one on my other four 3.7’s.
(I thought I posted that about six hours ago. But it was still sitting here now.)
 
Its a truism of life that at least half of our problems are self-inflicted;)
Certainly true for me. So much so that, of necessity, I have to think of them not as problems, but as “interesting situations”. 😊

Yes, good chance I’ll come across something silly. I’ve done. Funny you mention spark plug wires. About four weeks ago that was exactly what kept me scratching my head for a day or two. Switched cylinder one and two wires back to where they should be and hey!, worked a treat.
 
Is the exhaust manifold bolted up under the intake manifold? What makes you think it's running rich at lower RPM?
 
@seachicken Not sure what you mean re exhaust manifold under intake manifold.

A friend said he could see a drip within the carb while I was running it. The rpm would hunt between 2200 and 1000 two or three times before stalling.

Last night I rinsed the 180 carb (it’s a Quadrajet model 17083522) with gas hoping I might dislodge any dirt from the needles. I spotted a crack in the casing. Can’t say where it goes internally, but could be the problem. (Photo)

I’m going to put it back on anyway to see if rinsing worked. If not, I’ll try a rebuild on the other carb (model 17081299, from my 488).
 

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@seachicken Not sure what you mean re exhaust manifold under intake manifold.

A friend said he could see a drip within the carb while I was running it. The rpm would hunt between 2200 and 1000 two or three times before stalling.

Last night I rinsed the 180 carb (it’s a Quadrajet model 17083522) with gas hoping I might dislodge any dirt from the needles. I spotted a crack in the casing. Can’t say where it goes internally, but could be the problem. (Photo)

I’m going to put it back on anyway to see if rinsing worked. If not, I’ll try a rebuild on the other carb (model 17081299, from my 488).
Some engines the intake and exhaust manifolds are bolted together to transfer heat for cold running. Some of them are susceptible to cracking under the carb allowing exhaust into the intake, an overheat might not do any favors.

It's cracked where a plug usually covers that needle (think idle mixture?) If air is getting past that crack it would be an issue. Soak the carb in either Honda brand carb cleaner or sea foam, not gas. It won't dissolve varnish. Those carbs are susceptible to warpage on the base, put a straight edge on them. They often need to be filed flat. If you take one apart DM me, I've done a couple and learned a thing or 2. There's a major thing you don't want to do.
 
Before attempting or getting a carb rebuild, I decided to try a third carb, the one from the starboard engine which was running fine. Again, it made no difference in the port engine idling problem. So started looking elsewhere than the carb. Spark. Traced and checked every wire I could think of that might be relevant to the spark. Wire from coil Pos to slave solenoid was barely hanging on at the solenoid. Put it on with a new connector. Engine now idles fine. Doesn't make sense to me though, because that wire is only active when the key is in the Start position.
 
Then I got at the overheating problem (from Sea Trial 3). Checking the obvious things, including taking infrared temps all over the place. There was a pretty good temperature drop on the coolant across the heat exchanger, and good raw water flow at the exchanger outlet when i disconnected it, so I figured that wasn't the problem. After trying everything else I could think of, I consulted a pro who said to check for corrosion obstruction at the exhaust elbow anyway. Yup, looks pretty restricted. Live and learn.

I've cleared out as much corrosion as I can. Still doesn't look like full flow, but I'm about to put it on and see how it goes.
 
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