Carburetor float adjustment

[COB]

I have been having a heck of a time getting things to work. Symptoms are now this:
Engine dies when any load is applied.
Partial choke required to re-start, when warm.
Engine runs fine with no load.
After a cold start, I have to "goose" it a few times to keep it running until it settles down.

I have (not in this order):
Rebuilt the carb. Including truing up the mating surfaces.
Replaced fuel filters.
Replaced the fuel pump (facet.)
Checked the tank pick-up tube.
Checked the tank vent.
Replaced spark plugs.
Double checked the firing order.
Cleaned up the cap and rotor.
Checked for arcing wires.
Torqued electrical connections. (indigo ignition)
Cleaned the prop.

I think I have:
Suction. (I need to double check this)
A clear exhaust. (My config has concentric pipes all the way to discharge.)

I noticed:
The float's original "adjustment" was "full rich", i.e. the float was touching the housing when held upside down. I adjusted this to "parallel" with the housing.

After the carb rebuild, I got a gas overflow with the parallel adjustment. At this point I aggressivley adjusted the float lean. (I now believe the overflow was a stuck needle valve, not float setting.)

This seems to be the point at which the load problem started. I have re-adjusted the float 2x at this point, so that now its slightly "rich" of parallel.

My question is this:
How sensitive is the float adjustment? From your tech tip, it sounds like there is a fine balance between bowl level and mixture. Should I keep trying to find the correct adjustment, or should I start looking elsewhere.

As a side note, I can now take the carburetor off in the darK.

[Don Moyer]

COB,

Float settings higher or lower than parallel will have a direct effect on fuel consumption, but unless the float setting is grossly higher or lower than parallel, I don't see it as being the root of your current problem (lack of power in forward). You can confirm a reasonable fuel mixture in neutral by rapidly flicking your throttle forward to check acceleration. The engine should accelerate almost "explosively" with absolutely no hesitation and require that the throttle be retarded rather quickly to avoid over-speeding.

You don't mention compression. If you hold your thumb over each spark plug hole as you turn the engine over on the starter, is there enough compression to blow past your thumb no matter how hard you press?

If you have good compression, a reasonable fuel mixture as per the above check and normal ignition (including proper timing), it's difficult to know in which closet to look for your problem. This usually means that we're overlooking something, or something is dragging the engine down externally (like something hanging on the prop).

I know it's a nauseating thought, but your symptoms really do sound a lot like a timing issue (as in the case of plug wires out of sequence).

Don

[COB]

Compression OK

Thanks Don. I forgot to mention compression. Compression checks OK..95-115. Acceleration from idle, in neutral, is also OK as you describe. A wire issue is, truly, a nauseating thought. I'll check again. Also, I will tinker with the timing.

Note that this is an "engine dies" problem, not a "no power in forward" problem. It sounds like its running out of gas when I shift to forward, that's why I have been fooling with the float. I will verify the vacuum at the carb, and I think I'll bypass the gas (line) and filters with a new piece of line (fairly easy to do) to make sure I'm not sucking air or have a blockage.

[Administrator]

I was thinking that the engine was dying from lack of power, not from suddenly running out of fuel. Sometimes, if the idle mixture is very lean, an engine will not have enough power to engage forward while at idle. You might try turning the idle mixture on top of the carburetor in a 1/2 turn or so.

Don

[keith]

re :fuel problem from cob

hi cob...i went through the same senarios that you are.rebuilt the carb three times and relaced all ignition components.. still starved for fuel. got a a new carb from don moyer...and it runs like a new engine again. 1978 with 1200 hours. thanks don m. i was almost ready to repower..cheers keith

[dfoulds]

Carb leaking gas

Engine was running fine through confused seas throwing the boat around in all directions. We had shut down the engine and were sailing when one of the crew smelled gas. I checked the engine compartment and sure enough we had a fuel leak. I checked the obvious lines etc.. but could not identify the source so we sailed back to the dock. I took the carburetor apart and found the needle valve jammed between the float and its housing, kinda half way out. I bent the flap on the float housing to prevent the needle from coming to far out of its housing.
After reassembling the engine ran poorly so I took the carb apart and adjusted the flap again allowing a little more play in the needle valve. Everything seemed fine on subsequent trips.
The other night we went out to watch a fire works display and had the confused type seas again and the engine began to miss and finally stalled and would not start. Fortunately we were ready to anchor so we just dropped it where we were. When I opened the engine compartment I smelt fuel again and assumed it was the stuck needle valve. It seem as though the engine flooded it self while running??
I wasn't to happy about taking the carb apart again during the fireworks. I cleaned up the fuel and after 15 minutes or I tried to start it again. It started fine and we made it back to the dock without incident.
The problem now was that I could not trust the engine and had to determine what caused the problem in the first place. So I took the carb apart again adjusted the flaps and this time moved the floats slightly above parallel, maybe I should have adjusted them the other way after reading yours and Dons comments. The engine seem to run fine now but I am a little hesitant to trust it.
I bought Don's Carb video and it mentions fuel leaking out of the flame arrester but identifies the problem as an obstruction preventing the needle valve from seating properly. I am just wondering if anybody else experience problems with the needle itself getting jammed?

PS Cob:
My best time for the carb out/clean/in is now under 20 minutes. Never tried it in the dark though :-)

[Dave Neptune]

Careful

dfoulds, I would suggest that you either get a new float or redo the one you have. Only if the tabs have been tweaked could you loose to "proper" needle. Bending the tabs to get things back to right my require a pic of a good float. When tweaking the tabs be sure and hold by the tabs and tweak (bend) only the tabs and do not hold the float itself to tweak!!!!
Also be sure of the float setting. They can be a PIA if you are not familiar with tweaking on them and I don't think one would be to expensive.
Caution as the float can "open-up~crack" and leak internally if handled to rough, this will cause the float to fill and the carb will just flood again~be careful.

Dave Neptune

[dfoulds]

Thanks Dave:
I will keep an eye on it and if the last adjustment I made doesn't work I will buy a new float. The strange part is it just started on its own. I was surprised a simple mechanical devise could go wrong.
Fuel leaks are a serious issue and I don't mess around hence the last time I turned off all the electrical s and sailed into the dock.
Cheers!
Doug

[tenders]

It is possible the rubber coating at the tip of the needle is starting to fail so the float cannot do its job to the same degree.

[JOHN COOKSON]

While you're at it I would install a new needle valve and seat. The needle and seat are usually not interchangeable between manufactures.

Also what do you have for fuel filters? Maybe crud is blocking the needle valve open at times. As in rough seas stirring up stuff in the tank.

TRUE GRIT