placed in forward engine stalls, can restart it normally

[gary a gerber]

Engine has been running perfectly, shifting into reverse was normal. I found I had to adjust one notch on the forward tranny to get it to engage properly.
However, with engine in idle, when I shift into forward engine stops. I can immediately restart it as normal and achieve forward power.
The A4 has been running smoothly so is this stall at the forward shift possibly a carb setting adjustment?

[ndutton]

There are a few things it could be and yes, the idle circuit inside the carburetor is one of them. From first hand experience it could also be drag on the shaft imposed by a too-tight stuffing box that only gets tighter as things warm up and thermal expansion comes into play. Remember, at idle you have only 5HP shaft power (direct drive) so it doesn't take much to overpower it.

[Dave Neptune]

Gary, first welcome t the MMI Afourian Forum.

Yes it could be very simple. What is your idle RPM? Should be around 700 or so. Did you try to "richin" the idle a bit by turning in the idle screw a 1/4 turn or so?

How long since a tune-up?

If your idle speed is slow first try the mixture screw in 1/4 turn to see if the idle speed comes up a bit or it idles in forward. If no joy try the idle speed screw to get a few more RPM's and see how that works, then get back to us.

Also check to see the carb is on tight and do check the "scavange tube" to be sure it is not leaking air too.

Dave Neptune

[gary a gerber]

Thanks for the idle tips my first effort is to turn in the idle setting on the carb. I intend to get to that today. I knew I would get sound advice here.

Actually, I am not a new member to the forum I am a senior member. I appear as new because I added my middle initial.

[gary a gerber]

stalling when engaging forward

A follow up to the suggestion to give carb idle screw a quarter turn in. The engine runs smooth and strong but again, as soon as I engage forward she stalls. No problem engaging reverse. When stalled in forward gear it still restarts immediately when I turn the starter key. Note that on my boat the ignition panel is in main cabin readily in reach next to steps.

This problem began when I had moved my boat to a neighbors dock under normal power two months ago, no problems. Our dock was replaced and when starting to move her back, I had no forward power. I then adjusted the "forward adjusting collar" one notch and was able to move my Morgan back home once I restarted her after backing from their dock, although she moved weakly.

Again the engine runs smooth and strong and idles perfectly, it is only engaging forward that it stalls. I would appreciate any suggestions.

P.S. I am originally logged in back in 2008 as gary gerber with numerous photos.

[jcwright]

Hello Gary.

Here is a link to a thread describing a stalling problem that may be helpful. At entry #45 the owner found the solution:

http://www.moyermarineforum.com/forums/showthread.php?t=5422&page=2

As you will also see, the owner first checked several other possible causes, including some that haven't already been mentioned in response to your question.

Best regards.

jack

[capnward]

Reverse is half the thrust of forward, so it may be the engine is not strong enough to handle forward, because of a blockage in a carb jet, the idle jet in particular. Or it could be there is a restriction on the shaft from an over-tight stuffing box. Does it start in forward gear, then stop?
I keep referring to the episode I had when the engine would start and run fine in neutral and reverse, but not well in forward and would stall in idle with a load. It turned out to be an almost microscopic partial obstruction of the idle jet. It could only be seen by removing the jet and holding it up to the light, and even then it was easy to miss. After running a wire from a wire brush around in the jet, it ran fine.
Your one-notch adjustment of the forward collar may have something to do with it. I would consult the Moyer video on the subject. I am more inclined to suspect a carb jet blockage. And remember to change the fuel filters when "rebuilding" the carb.

[gary a gerber]

To recap my problem, when shifted into forward the engine stops, if I reach and just restart it, it will run forward in gear. Testing while tied up at the dock she will pull hard against the dock lines once I restart the engine and give power.

[roadnsky]

Did you check the stuffing box as Neil suggested?
Also, are you CERTAIN that your plug wires are in the correct order?

[Dave Neptune]

What is your idle speed? Try a few more RPM's and give the idle screw a 1/4 turn in. Often if your on the low edge of idle speed going into reverse is "easier" on the idle due to the gear reduction however going into forward the prop is more efficient and the load on the idle much more as it is a direct drive. May just be this simple.

Dave Neptune

[gary a gerber]

stalling when engaging forward (solved)

The stuffing box was rebuilt just last season and boat ran perfectly under power back from the marina. I did follow suggestion and add a quarter turn in to the carb idle. Situation remained the same: engine starts perfectly and runs smoothly but when shifted into forward while at a strong idle, it stalls, again I can immediately restart it while in gear and it runs as normal with forward power to the prop.

I know that a new adjusting collar with closer together notches was introduced in 1979. My 1970 has the original collar, when I first made a one notch corrective adjustment I did have weak forward power so I then, once docked again, make another one notch adjustment. So now I have strong forward engine power but that stall situation occurs when initially shifting.Is it possible the collar excerpts
too much pressure stalling an engine at idle?

I am addressing this in the forum since we all are A4 engine owners.

Follow up, sorry for the delay. I did back off one notch on the forward adjusting collar and that allowed for a smooth shift into forward and the engine ran smoothly. I believe I had inadvertently adjusted the collar too tight earlier. I really appreciate all the input from the forum readers.

[roadnsky]

The stuffing box was rebuilt just last season and boat ran perfectly under power back from the marina.

Have you adjusted it since the rebuild?
They should be set VERY loose when first packed and then gradually tightened over a period of time for the next few runs until finally set.
IF it is too tight it could very easily cause your symptom as described.

[JOHN COOKSON]

Tdocked So now I have strong forward engine power but that stall situation occurs when initially shifting.Is it possible the collar excerpts
too much pressure stalling an engine at idle?
s.

Maybe.
If the shaft is turning while at idle, in or out of gear, and the stuffing box is to tight when you rev the engine up in gear the engine will stall.
Feel the packing nut while at idle in gear.* If it is hot the packing is to tight. It seems to me that if the stuffing was so tight as to stall the engine the friction would generate a lot of heat in the stuffing box. What is the water drip rate out of the stuffing box when the shaft is turning? If cooling water is not in or through the stuffing box, and the stuffing is running hot you will wear it out in short order.
Does the engine stall when you shift into reverse also?
*Careful around moving machinery. An IR thermometer would be the best tool.

TRUE GRIT

[roadnsky]

Does the engine stall when you shift into reverse also?

Again the engine runs smooth and strong and idles perfectly, it is only engaging forward that it stalls.

Engine has been running perfectly, shifting into reverse was normal.

John-
It seems the problem is only in FORWARD

[Marian Claire]

Is there anything in the reversing gear that is moved during the act of engaging forward that could bind/stall the engine if not moving properly. My reversing gear/transmission knowledge is limited but if it runs in neutral and reverse, runs and even starts in forward but stalls as you shift into forward the only thing that is changing is the guts of the reversing gear as you shift. This has me baffled.
Dan
S/V Marian Claire