Mystery Shutdown (at just the wrong time!)

[JimPendoley]

OK all,
I appreciate the suggestions of everyone, being in a remote spot in late autumn its reassuring to know folks are out there.

Alls not lost though-hanging on the anchor and eating like a king in a very deserted and pretty part of the world is not all bad...

After lots of thinking-this is what I am imagining happened: on a deep heel (+20 degrees) the fuel vent goes underwater-its mounted high on the port stern counter but would likely submerge beyond 20 degrees of heel-pump can't draw fuel, heats up trying to suck fuel from a closed system and does not blow the fuse (if there is a fuse and I'm not sure there is), heats up the wiring on the ignition circuit and blows the tach. Boat flattens out and the engine runs normally-but tach is shot. It seems explicable-the facett pumps used to recommend a 20 amp fuse but now recommend a five amp fuse for this reason-
Tomorrow, I'm going to start the engine (it ran for charging purposes for a long time today) and put my hand over the fuel vent. If the engine shuts down relatively quickly, I think it's problem solved. If it does shut down, just to confirm the vacuum problem, I'll crack the fuel filler to see if it picks up fuel again.

Does this sound plausible? It does to me, but I had a glass of wine with dinner....
Jim

[RobGallagher]

Originally Posted by JimPendoley

Hi All,
Had a nerve wracking shutdown of my A4 today while sailing in gusty conditions. Symptoms were a "Clunk" and then a stuttering shutdown. Upon restart, I noticed my tach stopped reading. I've converted to an electronic ignition years ago. The engine ran a minute or two then shut down again. Oil pressure fine and so was the temp, alternator charging normally. I was motor sailing in boisterous conditions and a little on my ear. I would have thought it was sediment in the tank stirred up, but I do have a fuel water separator and I add gas stabilizer with every fill. This happened more than half a dozen times and it's a problem today because I have to exit a particularly long and tortured channel in the next few days.
The engine did finally stay running, but I kept the throttle low and the boat flat-still no tach. Is this suggestive of a coil breaking down? Prop seems clear, but I'm not going overboard to check-its November in New England after all...no water int the bilge.
Any suggestions on how to test the coil greatly appreciated.

Coil is a possibility, do you have a spare, or a friend with an A-4 who would loan you their coil for a test run? The tach giving up the ghost could suggest something. However, when the coil heats up and stops functioning I believe it shuts down the engine as if the ignition where switched off.

I would also check the fuel vent to see if the spiders have been at it. Insects/arachnids will build a home and it wills stop or slow the tank from letting in air as fuel is burned off. The engine will shut down, then, later restart as of nothing happened.

Are you getting full power? Can you make hull speed? Try running the engine under load at the dock to recreate the problem.

[tommays]

Vent could be clogged BUT if it was going under water it would draw a LOT of water into the fuel tank

[CapnBilll]

A safer way to test spark is to hold a neon light next to the spark plug wire.

My boat once had these symtoms, and after disassembling fuel system I found a mass of fiberglass fibers stuck in the fuel pickup tube. I would take a good hard look at ignition system as the tach reading comes from there. One of the two coil or tach may be bad.

[dabnis]

To rule out a possible fuel problem you might try hooking up a clean outboard tank with fresh fuel in it. If fuel delivery is not the problem, disconnect the tach wire and try another coil after double checking all electrical connections and possibly replacing all the high voltage wiring. Let us know what you find.

Dabnis

[LakeSuperiorGeezer]

Seems like you are trying to do trouble shooting without any resources so have to be a little more creative. The engine is running now without a problem so it is not possible to troubleshoot. You are just guessing. The following is not a definitive for sure diagnostic, but if the following criteria are not met, you know where the problem is. Here is one think you can try. Is the fuel tank located above the carburetor? If so the fuel pump could be dead and the engine would still run because of gravity feed. If the fuel tank is below the carburetor, pull the fitting at carburetor and slip a hose on it making sure it will not leak, maybe need a clamp for this. Becareful with matching hose size. Use a rag or better use a container to capture any fuel, or use a rag under a container. There is the fire and explosion problem with gasoline. Turn on the ignition and see if there are several quarts of fuel pumped per minute into a container. This could vary with the exact model of Facet pump. Find the pump model number and I can look it up is you like If the carburetor is below the fuel tank, fuel will pour into the bilge if you loosen the fitting so you must turn the fuel off at the tank or disconnect the tank until you have the hose on the delivery pipe. You can also check any fittings before the filters to check for debris. If the filters are after the pump, check the fitting where the line goes into the pump.

Another thing to try is take the center wire from the distributor and place it half an inch from metal. Tie or tape down if needed, but make it half an inch. If there is no smell of gasoline around the engine, crank and see if you get a nice fat spark. Sometimes when an ignition is going bad, there is enough spart to start the engine, but it looks weak, jumps a quarter inch or less and is likely to quit any time. Be careful with the spark as these modern high energy systems can deliver enough amps to be lethal. Also, magnetos are very dangerous. My dad knew a fellow killed by a magneto. By the way, try the spark test first before opening any gasoline lines. Less chance of a fire

[saillowey]

When I had issues with the coil, it acted exactly like a fuel system issue. It would run, then start to sputter at an increasing rate, then shut down. There is an easy check the coil. Look at the bottom of the coil. If it's not flat, but rounded out, you need a new coil. The heat has distorted it to a point it's pushed out the weakest point. If it's round, take it down. When you buy the next one, mount it on the bulkhead. I'm sure I can look up which one I bought. I know it was an Echlin model from Napa. Most of the parts can be had locally if you have a Napa store. I know I also bought the wires and cap from there as well. Seem to me the cap was also used on a 1974 Chevy Vega.

Good Luck

[LakeSuperiorGeezer]

Need to do something as the engine is likely to quit when you need it the most.