[Public-List] A4 Question

[Gordon Laco]

My A4 always runs best in the winter.  Actually, come to think of it, my
boat points higher, reaches faster, wins more races and when cruising finds
more beautiful anchorages in the winter.  Every thing is more perfect.
Everything.

And yes, I have to admit, that's all because she's ashore in the winter and
the races and cruises I participate in are all in my dreams of next
season....

Gord #426 Surprise


On 06/01/14 4:29 PM, "Stephen Gwyn" <stephen.gwyn at nrc-cnrc.gc.ca> wrote:

> 
> My A4 sometimes runs less than perfectly in winter. It's
> usually hard to start if the temperature is close to
> freezing. Then it will run fine for 10-15 minutes, before
> losing a lot of power in gear. I'll motor out the marina
> in gear at idle, then speed up when I get out. A minute
> or two after that, as I'm in the middle of the current
> (and the rocks), the engine starts to slow down. Opening the
> throttle brings it back up to normal power, and after 1-2 minutes
> the engine starts to over rev. I then close the throttle
> a bit and the engine runs fine for the rest of the day.
> 
> The loss of revs only happens sometimes. It only happens
> before the engine reaches operating temperature. It never
> happens in summer.
> 
> I have some theories:
> 
> 1) Ignition system is damp or otherwise compromised by cold or
> possibly age. Damp isn't good for the points in particular.
> I replace the points, condensor, cap and rotor
> in the spring, so in winter they are at the end of their service life.
> But I don't think this is the case, because then the engine would
> run poorly from the start.
> 
> 2) Condensation in the fuel tank, which then gets into the fuel.
> More likely. Winters in Victoria are very humid and certainly the boat
> gets a lot of condensation in winter. But I have an over-sized
> fuel filter/water separator which I change regularly, so I'm
> moderately sure that's not it.
> 
> 3) Carburetor icing. If you put your hand on the carb throat
> when the engine is running, it's a lot cooler than the ambient
> temperature, and certainly a lot cooler than the nearby manifold,
> which gets quite hot. On cold humid days, I've noticed a thin coating
> of frost on the outside of the carb. My guess is that frost is
> forming on the inside of the venturi, restricting the flow of the fuel/air
> mixture into the manifold and into the cylinders. Eventually, however
> the manifold fully warms up and starts conducting heat to the
> carb. The ice melts, the venturi clears and the engine starts
> working normally again.
> 
> SG
> 
> 



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