Mystery Shutdown

[JimPendoley]

Hi All,
So I'm anchored at a very remote protected spot in Northern New England getting ready to troubleshoot my A4. I started shutting down in boisterous conditions on a fair heel (20 degrees) while approaching the channel-I was motorsailing.

Symptoms were a sputtering shutdown. Before you say "dirty fuel or sediment stirred up" I have a racor fuel/water separator and add Stabil fuel stabilizer with every fill up. Key symptoms were an audible and soft "thunk" as though I'd hit a lobster pot and then a stuttering shutdown. Another key symptom is THE TACH stopped working. The engine would restart, run a minute or so and shut back down in a sputtering way. This happened a half dozen times. I finally flattened the boat out and got the engine started and ran in on lower power with out incident-but STILL NO TACH. No water in the bilge and prop seems to turn freely.

From reading other threads I am guessing intermittent coil failure or facet fuel pump failure. I have an Ignitor ignition and the fuel pump is wired with an oil pressure safety switch.
Any suggestions on simple diagnostic troubleshooting greatly appreciated as i am far away from help.
Thanks
Jim Pendoley

[smosher]

Where is the tach connected ?

Steve

[Dave Neptune]

Jim, welcome to the forum.
As you were heeling a bit you may check the oil level. If it is low it could cause the OPSS to go intermittent and cause a sputtering stall~~however doubtful. A sputtering shut down does imply a fuel related problem and the electric pump going off and on could maybe do the same.
Re your tach quiting it may not be related as you did start back up. I don't think I would worry to much about the tach at this time.
Since you are stuck I would drain a bit of fuel from the float bowl just to confirm water in the fuel is not the problem.
How did it run once you got her stood uprignt again? Mostly did you have a bit of power available or did you try to throttle up a bit? Did you take a look at the plugs and if so how did they look? I would also check all of the ignition connections at the coil and especially the key switch. If the ones on the switch are even suspected I would try to hot wire her and see if that helps. While motor sailing at 20 degrees you may have shook something up by loosening an electrical connection or even shook some KRAP loose in the tank and the filters are a bit plugged.
We need to narrow some possibilities down a bit.

Dave Neptune

[Loki9]

Is it a mechanical tach or electrical? It's conceivable that an electrical tach could short out the ignition circuit in some way. Perhaps healing over allowed a loose wire to contact something it shouldn't?

[edwardc]

A "thump" and the tach quit? My first thought was that you threw an alternator belt. Some tachs use an alternator takeoff to get their signal. No belt, no signal. Easy to check!

And if you've got some corrosion in the battery wiring, maybe the loss of the alternator might drop the voltage enough to run rough. Not too sure about the possibility of this one though.

[lat 64]

Your're probly in good hands here, but I would add low oil level to the list of checks.

Low oil level, boat heels and flops around, oil pump goes dry, oil pressure drops, fuel pump shuts down and engine runs down on remaining gas in carb.

Just a wild guess

Good luc,
Russ

[Marian Claire]

Another welcome. I know you said not to ask but do you have a spare fuel filter? Prier to cleaning my tank I had shut downs in rough conditions because the filter was doing its job and becoming clogged with crud. Dan S/V Marian Claire
Edit: The first thing I would check is flow to the carb. Disconnect the line at the carb, bypass the OPSS and see what flow you have. Is the pump ticking? If low then I would check all the connections, if one is loose it could be sucking air and recheck. If low replace the filter and recheck. If still low the pick up tube could be clogged and blowing back thru the system could clear that. If you have good flow then we can move to the carb, OPSS, coil etc. Could you give us a description of your fuel system set up from tank to carb? Do you have a spare fuel pump?

[JOHN COOKSON]

Originally Posted by JimPendoley

Key symptoms were an audible and soft "thunk" as though I'd hit a lobster pot and then a stuttering shutdown. Another key symptom is THE TACH stopped working. The engine would restart, run a minute or so and shut back down in a sputtering way. This happened a half dozen times. I finally flattened the boat out and got the engine started and ran in on lower power with out incident-but STILL NO TACH.

Was the bump the fuel tank shifting? Did a shifting fuel tank somehow goof up the fuel delivery system to the engine? Maybe by crushing the outlet fitting on the tank? Did a shifting fuel tank somehow crush the tank vent?
Was there enough fuel in the tank so you were getting a solid pull of fuel when the boat was heeled?
Did a shifting fuel tank crush the lead to the tach?
Just trying to connect the dots using the information presented...........

TRUE GRIT

[sastanley]

John,

I never thought of that, but now that you mention it, certainly a possibility...I had my tank shift on me the first few months after installation when one of the hold down clamps popped loose!

We need the OP to come back now...we have certainly given him LOTS of possibilities!!!???

[JimPendoley]

Hello Afourians,
I'm safely back from my little excursion, snugged into my winter slip (I'm a liveaboard) in NH. Here is the update: Engine ran for several hours while anchored and pushed me home through flat seas at 5 1/2 knots for a three hours. Not even a hiccup. Only thing I did was add oil to the fourth line on the old style dipstick and drain the fuel separator bowl (the gas looked clean).

I added oil on the suspicion that the OPSS was possibly being deprived of oil. I had always followed the original Universal recommendations for filling only to the second mark on the dipstick for a horizontal engine (not installed on an incline), but I share other posters belief that it might be causing the switch to shutdown if deprived of oil on a steep heel. I now have oil filled to the fourth hash mark on the dip stick.-from what I've read here or elsewhere overfill is not much of a risk on these engines.

I still don't know for sure if the oil pressure switch was the cause or not. I think I've at least eliminated oil deprivation to the swich as a cause in the future. If it was the switch though, I don't completely understand how the tach shorted-could a stuttering of the ignition short an electronic tach?

I'd also like to thank everyone for your thoughtful responses. I was in a ticklish spot and all of your input was reassuring as I puzzled over the problem.

[JimPendoley]

Afourians,
One other angle that another poster mentioned has me thinking-my feul vent is high on the port stern quarter and it absolutely could have let water into my tank. I have a facett pump and I did drain my filter and found no water-but this exact series of symptoms happened to me last year in similar conditions ON THE SAME TACH and at THE SAME ANGLE OF HEEL. It's nerve wracking and how to tell if it was the OPSs or the vent I'm not sure.

I guess water in the tank would be the primary indicator, but the gas ran clear from the bowl. All of which makes me wonder: how do you install a fuel vent so it can't suck in water?

Our list of culprits is now:

low oil and OPSS Shutdown -would this affect the tach via ignition?

Intermittently failing fuel pump with high electrical draw damaging tach

water in the fuel via vent submersion

I'm thinking the tach failure and the lack of water in the fuel bowl eliminates the fuel vent

[JOHN COOKSON]

Through or at the stern of the boat on the centerline as high as possible.

TRUE GRIT

[JOHN COOKSON]

Originally Posted by JimPendoley

It's nerve wracking and how to tell if it was the OPSs or the vent I'm not sure.

Jim
As you know the easy way to diagnose a blocked fuel tank vent is to loosen the fuel fill cap so the tank can pull air in that way.

As Dan suggested watch the oil pressure gauge to diagnose low oil pressure. The spec on the Moyer OPSS is 6 +or- 2 PSI. You can temporally short across or bypass the OPSS if it is suspect.

TRUE GRIT