1980 SN stalling when hot / won't restart

I should note; engine is Commander 351, Holley 4160 Carburetor.

When the engine dies or won't start, do you have spark? What's in the distributor? A EI module? If so, is the coil matched to the module? Does the coil require a ballast resistor. Is the coil getting hot to the touch?

8122pbrainard wrote: When the engine dies or won't start, do you have spark? What's in the distributor? A EI module? If so, is the coil matched to the module? Does the coil require a ballast resistor. Is the coil getting hot to the touch?

Brainard, thanks much for your response. Here's the answer to your questions;
1) Do you have spark? YES
2) What's in the disti? EI
3) Is the coil matched? NOT TO MY KNOWLEDGE, NO

Longer answer to question 4, so I'm delineating between it and the others. My diagnoses and repair efforts have circled largely around the coil, to your point. Initially I replaced the coil early last year as part of routine electrical system maintenance with a new one that matched the existing one exactly (which had always performed well). Once the problems started occurring and I researched a bit, it became apparent the the coil i'd replaced with was possibly an "automotive" version and didn't include a ballast resistor which i believe the system requires. So, we replaced that coil with the right one and right away, it seemed fixed, but first launch this season and the problem cropped up again right away.

I'll send/attach photos of the parts of the system we're referring to as soon as I can take some this evening

Thanks very much for your help here..

RammerJammer wrote: I had this issue the first few months I owned my boat. I simplified the electrical system by removing some mods the PO made (like gunnel LED lighting and ground splices) and I got a new Marine Starting battery (the PO had a deep cycle battery). I have not had the stall/no-start happen again. That was several years ago. I had not yet learned to troubleshoot with a VOM so I can't get more technical than that. Not sure if this helps.

Thanks Rammer, there are almost no mods on my boat and I've replaced the battery twice unfortunately. I do think it's possible that power delivery is somehow the problem, but if it is, I think it's somewhere else in the system.

scootdogydog wrote: Three main things you need to start a boat (hot or cold) spark, fuel, and compression. When it gets hot, you can check for spark by pulling a plug and grounding it. You can check for fuel by looking in the carb. I assume that your compression is not your problem. It should be pretty simple to isolate if it's a spark or fuel problem. If you want to try fuel, pour a small amount of fuel down your carb.

Thanks Scotty, ya, this is the part of the symptom that's kind of hard to describe. Compression is not an issue, as you surmise, but I also get spark and fuel both when the problem happens. As mentioned, it's not that it won't start at all, it's just very, very difficult and then won't stay running. Sometimes with extra fuel and fluttering the throttle it'll stay alive for a minute or so, but then will stall again and die. It acts very much like a fuel, air or possibly power delivery problem, but I'm just stumped on which parts of those systems could be the culprit considering the items that I've already eliminated, replaced or repaired.

scootdogydog wrote: Have you considered an inline spark tester? That'll tell you when it's starting to die, if you're not getting spark until you give it more fuel

I have not, never heard of one as a matter of fact, but I'll look into it.

Is this a situation where you're running along at 30 mph or so and it quits or is it you come down to idle speed and it quits.

If it's the latter, I once had this problem drive me crazy for a while and it turned out to be the gasket between the carb spacer and the engine was in pretty bad shape and as things heated up a vacuum leak at that gasket made idling next to impossible, but let it cool off and things were good again.

Not all spacers are the same but here's a picture of the bottom of a PCM spacer where it meets the intake manifold Not a lot of sealing area on the outside and some replacement gaskets just don't fit right so you have to make sure the gasket is big enough to seal all the way around the outer edges

It may not be your problem at all but since you say you have spark and fuel when it quits, it's probably worth looking at if it only quits at idle speeds. If it quits at high speeds, it's probably not the issue

Also sounds crap in the antisyphon valve, clogged cone screen in the fuel pickup or a clogged tank vent.

I had a 1980 myself and I had a person rebuild the carb who knew what they were doing and upon reinstalling the carb, it did not work properly. I then sent the Carb to Carolina Carburetor Specialist in Wilmington, NC 910-762-4695 (Butch). They once again did a rebuild and actually did a remanufacture of the unit. They found that one of the floats was slightly out of spec or too heavy. Not filled with fuel from a leak, just out of spec. I would of chased my tail forever to have found this. JoeinNY and TimBj, tried very hard to help me at the White Lake Mini several years ago but we could not find the issue.

When Carolina Carb Specialist does a remanufacture, they put the carb on a Flow Bench which simulates an engine. They dial it in right there so it is Plug N Play. It was not cheap, but it saved my summer and the boat ran better than ever. I also realize you are in Washington State, but you could ship it to be taken care of. I know one from this site that has used a company in Jacksonville, Florida, name slips me, that sells on e-bay with great results. They send you a remanufactured carb and you send them your core of credit. They have several actual engines on stands that they use to dial in the carbs.

I probably would of come out cheaper if I would of just purchased a new Holley, but I have heard people on this site have issue right out of the box with them. I am not able to dial them in. Also, the older carbs have the spacer with the PVC Vent Line on them. The new Holley Carbs have that built in so then I was going to have to find a new spacer.

Being the boat was a ultra rare, d*ck Pope family / Cypress Gardens , Bush Gardens, 1980 Master's boat and even pulled the 1980 Moomba Master's I decided a new carb might devalue such a rare boat.

In my opinion, it is getting harder to find people familiar with Carbs on the shop level. Fuel Injection has been around so long I consider it a dying art. Maybe I am wrong.

Morfoot wrote: Is that coil Oil filled or epoxy filled? Oil filled coils DO NOT like horizontal installations as a norm.

Oil! I'll see if I can change the orientation, worth a shot!

I found loose wires from the trans cut out was causing intermittent issues.

also could be fuel.   Sort of a vapor lock could be happening, Weak pump or something internal in the carb or if there is a check valve that could be an issue.   
Carter fuel pump isn't that expensive, if its old then put in a new one.   

JoeinNY wrote: Lots of good advice above but also two very typical things to look at Low voltage issues due to bad ignition switch or weak wiring... check to see how many volts you are seeing at the coil with the engine on when you are having a problem. Also it sounds to me like you are simply flooding the engine - look down the carb throat when it wont start and if you see fuel dripping that is bad. If it is flooding it will start with the throttle open - don't pump the throttle, don't wiggle the throttle - open it wide open and crank it to allow enough air in to match the amount of fuel you have - then crank it for a bit. If it starts like that then you need to fix and or adjust your floats.

Thanks Joe, i'm going out this weekend so i'll get a voltmeter on the coil when i first start it and again when it stalls (inevitably) and see if there's a difference.

As far as the flooding goes, there is no fuel dripping when it won't start, it pumps fuel into the throat of the carb as it should when you pump the throttle, but I honestly can't say for sure if I've tried the wide open throttle technique so I'll try that.

It just struck me, there's one thing I have failed to mention that never seemed related, but if the main problem is a voltage issue, this could be pertinent. When the issue occurs and i have to try cranking a lot to restart, the starter solenoid sometimes will not disengage even when I turn the key back to "off". It just keeps cranking and i have to shut the battery off to get it to stop. That issue only cropped up later last summer so it wasn't happening when the initial problem started to occur, but possibly could be some sort of clue...?

JoeinNY wrote: Also it sounds to me like you are simply flooding the engine - look down the carb throat when it wont start and if you see fuel dripping that is bad. If it is flooding it will start with the throttle open - don't pump the throttle, don't wiggle the throttle - open it wide open and crank it to allow enough air in to match the amount of fuel you have - then crank it for a bit. If it starts like that then you need to fix and or adjust your floats.

+1   I too thought of mal adjusted floats.   your carb guy adjusted the floats on his bench, level.... they may need a little tweaking because of the angle your engine sits at.

your coil being horizontal for a while may have caused a heat related issue.   This might mean that a replacement is needed, not just a relocation.   If the damage is already done,you won't know the coil is malfunctioning until it is heated up.   IMO intermittent coil problems are hard to diagnose.

also to note - your rubber fuel line with clamps is not USCG approved, you need to get or bend a fuel line out of brake line or purchase the flexible one from Skidim.   While not USCG approved, you could also get a flexible aviation style hose from the pump to the carb, using AN fittings and a stainless braided fuel line.   Jegs and Summit have the Holley side of the fittiings... this is probably way more trouble than just ordering the line from skidim though.
one last thing... The transmission switch won't affect your runnability, it only affects the starting circuit.   if you question it, an easy work around is to jumper the two terminals on the switch.

As long as you have spark when the issue occurs, IMHO this is a fuel issue when hot.
Friend with an '83 had the exact same symptoms you've described.
I replaced the intake manifold gasket and the carb base gaskets and....voila.
Cured a hot vacuum leak.

go through everthing