Another Atomic 4 Issue

[Bardo]

I am able to start my A4 no problem, get out of the slip and out to sea (a very short sea and anchor detail of about 5 minutes). I sail around for awhile, and then when I am ready to come back in, the motor is hard to start. When it does start, it runs very roughly, and won't take any load without stalling. It gasps and pants along (starved for fuel, or air?) but after 5 minutes or so in nuetral, clears instantly and revs up to normal operation. I have a theory, but would like your opinions of possible causes. I am not a skilled mechanic, nor do I play one on TV.

Thanks,
Freeman

[RichH]

1. beginnings of a blown head gasket (between cylinders)
2. dirt/water in carburator emulsion tube causing intermittent 'fuel/air' ratio problems. Just a 'speck' of crud on the side holes of the emulsion tube will sometimes do this.
:-)

[poopdeckpappy]

Originally Posted by Bardo

I am not a skilled mechanic, nor do I play one on TV.

Thanks,
Freeman

But did you stay at a Holiday Inn last night

[sailhog]

The sound of the shutdown sounds like fuel starvation. I've been dealing with a similar problem for a while now, and just solved it. Try the following:
1. Replace the element in your water-fuel separator.

[sailhog]

Somehow I posted without finishing the post... Anyway, here goes again... The sound of the shutdown sounds like fuel starvation. I've been dealing with a similar problem for a while now, and just solved it. Try the following:
1. Replace the element in your water-fuel separator.
2. Replace or install inline fuel filter between fuel pump and carb.
3. Remove air filter, and squirt in a little carb cleaner
4. Make sure vent is clear.
5. Replace stale fuel (if it indeed is stale) and add fuel stablizer and Marvel Mystery Oil.
6. Drain water and/or **** out of drain plug at the bottom of carb. Drain it into a clear glass so you can see the quality of the fuel in there.

These are the easy fixes. There's a good chance one or a combination will solve the problem. If not, make another post. Be sure to run the blower after you muck around down there before starting the engine. Good luck.

[capngregg]

If this engine hasn't been given a lot of TLC over the years it could be some or all of the items on Sailhog's list. It certainly sounds like a fuel/carburetion problem. (maybe even a sticking float or needle valve)

Filters and the like can play some funny games. (especially at sea or navigating back into the slip) Also if the plugs, points, condensor and plug wires haven't been replaced in a known interval of time you might consider replacing them as a matter of preventative maintenance.

Ensuring the carb. is clean and in good shape will probably give you the biggest (er) bang for your buck. The old Zenith up-draft carbs are very simple to take apart and put back together if you're up to trying something new. Just make sure you catch all the fuel during disassembly and watch for leaks. Fuel tank maintenance is also advised and check the fuel pump output.

Good Luck!

[cardiacpaul]

first things first... before you go replacing parts willy nilly, see if it is the fuel problem... check the bowl (if so supplied) under the fuel pump to see if theres crud in it. (crud, IS a technical term)
next remove lower carb bowl by removing brass bolt at bottom of carb, tap bowl with somthing soft, use nothing harder than your head, its pot metal, pretty fragile. clean out the crud there. Gently flop the brass floats a couple of times. reassemble. It should be fine with new filters after that.

[Bardo]

But Cardiacpaul, There IS nothing harder than my head (just ask my wife). thanks for the gouge, I'll go there first.
Freeman

[hellosailor]

Doesn't make sense. You're doing a cold start and it works fine. Then shutting down, presumably the engine is going cold again, and it won't run well cold for a second time "but after 5 minutes or so in nuetral, clears instantly and revs up to normal operation." which means it will once it gets HOT.

I'm thinking maybe vapor lock in the carb, since that's a transient condition related to heat and running, and after that 5-minute idle sucking colder fuel in, maybe that cools the carb enough to make it run well again.

A head gasket would be more likely to be a problem whenever the engine was at "the same" problem temperature, so it would happen more often, I think. A simple compression test (buy or rent or borrow the tester) would check that.

If your carb hasn't been stripped down in the last year years--strip it down and do a major rebuild on it. They simply require that as maintenance for proper performance, maybe compounded by old stale gas, which should be pickled if kept around for more than 60-90 days.

[RichH]

Hellosailor brings up a good point ......


If the fuel delivery line has been changed to copper tube and has been run close to the outlet header of the (hot) exhaust manifold ... could be a cause for 'vapor lock' if you have a weak mechanical fuel pump. If so, next time this happens wrap a water soaked bath towel on the fuel line and see if this doesnt immediately correct the problem. If it does, get an electric fuel pump (www.moyermarine.com or www.Indigoelectronics.com and/or relocate / insulate the fuel inlet line.

Don Moyer the world's 'guru' has a comprehensive Maintenance Repair manual for the A4. Contains all the info for a complete rebuild or simple troubleshooting. Was about $50.00 last time I looked. One 'solution' found from Dons 'manual' would pay for itself. www.moyermarine.com
Don lives near Chestertown, MD .... sail on over and get a copy.