Engine dies randomly it seems.

[alex37]

Hi, I just bought an old Pearson 28. It seems like a great boat. Test sail went perfectly. Engine cold started right up and ran great. Then 2 weeks later, it had not run in that 2 weeks, it started with some effort and ran great for about 25 minutes and then died. Quickly. No sputtering. Just like you turned off the key. It started back up and we made it into the slip before it did it again. It doesn't matter if its in gear or not. It doesn't matter if it has a load on it or if its idling. Here's the tricky part. I'm not very mechanical. I'm worries that i wont understand your responses. Feel free to talk down to me.

In my opinion it isn't gas. So, what should I look at next?
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Bdsm flogging

[msmith10]

Alex,
Tell us a little more about your engine:
Is it new to you?
Has it been maintained well?
Has anything been done to it such as ignition tune up, carb cleaning, etc?

I'm quoting an old post of Don Moyer's that I always keep in mind when troubleshooting:

An engine requires three basic things to start: Fuel, Ignition, and Compression:

1) FUEL: Remove the flame arrestor and check for the presence of raw fuel. If the choke is closed completely, there should be raw fuel puddled in the bottom of the intake throat within 15 to 20 seconds of cranking (3 or 4 five-second attempts). If the carburetor intake throat is "bone dry", the reason for the non-starting is either a problem in the fuel supply that prevents the fuel from getting to the carburetor, or some problem within the carburetor that prevents the fuel from getting through the carburetor (most likely a blocked main jet).

2) IGNITION: Remove the secondary lead from the center of the distributor cap and hold it approximately 1/4" from the cylinder head while someone cranks the starter. You should see a good arc between the end of the coil lead and the head that can be stretched to 1/2" or even 3/4". If you see no spark, the reason for non-starting is clearly within the ignition system, most likely a breakdown within the primary ignition circuit. This check does not validate that timing is correct, so if the timing was altered during recent maintenance, it would be a good thing to reset the engine to number one TDC and recheck for proper timing.

3) COMPRESSION: With all spark plugs removed, hold your thumb over each spark plug hole sequentially to check compression, as someone cranks the engine for a second or two with the starter. An Atomic 4 will usually start if any two cylinders have normal compression as indicated below.

Do the above checks first. If you don't understand any of it, post back and ask. Don't be intimidated by the engine or by asking questions. A person who is really an expert in something is the guy who can explain a complex principle to anyone so they understand it. I'd recommend you buy Don's manual. Also, search this forum for "sudden engine shutdown" and you'll get a lot of info.
You're right to suspect ignition rather than fuel for sudden shutdowns, but don't rule out fuel. When the engine dies and restarts after a short time, it may be getting starved for fuel. Do the above checks.

[sastanley]

mechanic

alex - We'll turn you into a mechanic yet. - welcome to the forum.

Mark's suggestions are all good ones.. I will make one comment to add: do not crank the engine for long (when it wont' start & run) with the sea water intake open...the engine has to be running for it to expel the water out of the exhaust..if you crank and it won't run (~15 seconds, varies by boat & configuration) the exhaust system fills up with water and then backs into the cylinders creating a BIGGER problem.

So, when troubleshooting start/run problems and using the starter...close the thru-hull...once it is running, you can head down below and open the thru-hull again.

My first guess is a bad coil.., they are electrical components and sometimes fail after being used for a while and warm up. I remember similar symptoms on my boat when I was a newbie last year and I finally figured out it was a coil after replacing almost everything else (& thought it was a fuel problem at first) when my engine would run for 45 minutes and just shut off. Moyer sells one on their site for a reasonable cost.

keep the comments and Q's flowing...we'll help you out!

[Mo]

People Mechanic.

I agree with SAStanley. Really sounds like you coil is failing. Coils don't fare well with heat. I personally moved mine off the engine and onto the closest bulkhead. It just required a new longer coil wire. With that said, I never did have a coil problem. I just remember how coils always failed on my first cars. The coil in mine is 3 years old and I keep a spare on board....just something to think about.

Good luck with it.

[sastanley]

maurice,

I also moved my new coil to an adjacent bulkhead...the old coil (which is now my backup and at last check would run in 45 minute intervals and I think was original to the motor in 1977) is still mounted on the engine. My new chrome Flamethrower is performing admirably

[FelicityRebuild]

Newbie too

I have no idea what's wrong with your engine , but I did want to comment on the newbie aspect of your post. I've never worked on an engine before in my life, previous to 2 months ago when I decided I needed to tackle my boat engine. I went full throttle (pun intended) on it and after it sat for four years and siezed up, is now in parts, completely broken down, in my shed undergoing a complete rebuild. It's an amazing learning process and this forum has been a wealth of information. I'm hoping to have helpful information to offer soon. Welcome and good luck.

[hanleyclifford]

engine cutting out

Another vote for suspecting a bad coil; however, I would first eliminate the ignition switch especially if it is an old keyed version - bypass it and any other links in the primary circuit that look old or questionable. But it is a fact that a bad coil will cool off and then run again for a short time and then quit again.

[Kelly]

We're all offering advice based on experience or reading about others trouble shooting similar problems. I agree with all the advice given here so far (except maybe for the coil overheating on the block- this has been discussed on the forum at length).

I'll add that your symptoms could also be explained by faulty connections in your engine wiring, and especially in the wiring to ground. Heat variations can wreak havoc on circuits with cold conditions providing good electrical contact and heating (i.e. expanding) opening circuits at the worst moments.

I would check your main connection to ground which is sometimes subject to corrosion. Clean the circuit from the bottom up (from the engine block connection backwards) and make sure your problem isn't due to something simple and free to repair before replacing parts.

With all that said, don't forget the capacitor if you're running with the points system (not the electronic ignition). It's easy to replace, very inexpensive and can also cause your symptoms if failing.

[David Masury]

I am going with a bad wire connection some where and then the coil. Nothing that you have described sounds mechanical. But learning to do all your own owrk and matainance with give you more confidence in the engine.

David

[alex37]

Thank you all for the great responses. To answer some questions: 1. I bought the boat from a broker, so I have no contact with the seller. I'm trying to change that. 2. The engine seems to have been well cared for. 3. the seller had recently replaced the distributer cap. Other than that, I think I will try replacing the coil. Are there any tips or tricks to that?
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BODY SCIENCE

[hanleyclifford]

coil replacement

Since you have decided to replace the coil, does this mean you have eliminated problems in the primary ignition circuit?

[msmith10]

Alex,
You will get frustrated and poor if you replace parts randomly or on hunches. The fact that the po replaced the dist cap hints that there he was having a problem and tried that-- it's easy and cheap, but it was probably wrong. Test what you can test. Test the output of systems first. If the output is good, then you don't need to test back down the line. When Don recommends the spark test by grounding coil output to the block, you've tested the output of the ignition system up to the rotor.
It's true, you could have intermittent failure of the coil as it heats up, but don't go looking for zebras until you've ruled out more obvious problems. Do the spark test first. If that's no good, we can walk you through the primary ignition. I'm with Kelly-- I'd clean, check, and tighten all your grounds, which is good maintenance anyway and doesn't cost anything.

[alex37]

Here's an update.

I replaced the coil. I also checked as many of the grounds as i could. I removed, cleaned and re-attached them.

When I removed the wire from the coil, there was oil in it. It seemed to be in the wire and in the coil. There was also oil in the other end. (the distributer cap end) Oh, and I was wrong about the seller having replaced the distrubuter cap. It had not been replaced. One of the mounting screws is badly corroded and will have to be drilled out.

The engine still died ramdomly. It started much more easily after it died though. So now, after talking to a few mechanic friends, I'm pretty sure I need to get a new distrubuter cap and points. What do you all think?
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Body Science

[sastanley]

alex,
I've gone to electronic ignition, but I seem to remember reading somewhere that the condensor could also give "random dying" symptoms..it is even cheaper than the points, but they are on the plate together, so I'd just replace both. When I bought my boat, I found 3 or 4 condensors, 3 or 4 sets of old points & a distributor cap or two floating around in the tool box.