3.0 - what closes my choke?

[smartwork]

I'm examining my choke and see how the coil operates (and does correctly). Does the coil push the choke open or push the choke closed? There's only a tab (not a loop on the coil), so it can only do one or the other. And then, what does the other action (open or close)? I don't see a spring anywhere. I

If the choke pushes closed, what pushes it open. If the choke pushes it open, what pushes it closed?

Thanks!

 

[HT32BSX115]

Re: 3.0 - what closes my choke?

Howdy,

Difficult to say without knowing the make and model your choke is on.......


If it's an electric choke. There's a 12v powered heating element that heats a bi-metallic strip which moves the choke to the open position when it gets hot.

This usually takes a finite amount time, which just happens to be similar to the amount of time it takes to warm up the engine.

Since I only use my boat in warm weather.....I disconnected my choke altogether. It runs just fine.

Your mileage may vary........


Regards,


Rick

 

[smartwork]

Re: 3.0 - what closes my choke?

Thanks, Rick. It's a carbureted Mercruiser 3.0 LX on a 1997 Bayliner Capri. The engine runs well, but would like it to fire off more quickly - if possible without pumping the throttle (not sure if that's possible). I wasn't sure if the coil pushed the choke open or closed, and then I also wasn't sure what did the opposite action.

If the coil pushes the choke open, what closes it? I don't see any spring on the carb or the diagram of the carb to close it, so if the coil cools the choke (as it is now) remains open.

-shaun

 

[P 0 P E Y E]

Re: 3.0 - what closes my choke?

When the spring is at ambient temperature, the choke is in the closed position.

This will cause a lower pressure at the opening of the main discharge nozzle due to the airway being restricted by the choke plate. A richer mixture will occur for cold engine operation.

When the engine warms up, the spring expands with heat causing the choke to open. This provides a leaner mixture due to a larger opening at the inlet of the carburetor.

When the engine cools down, the spring returns to it's retracted state and the choke closes.

Knowing this, you can look at the spring and do the advanced math if needed.

please excuse my sarcasm.

 

[maxxman04]

Re: 3.0 - what closes my choke?

the coil generally pushes the choke open. as stated, if your choke is electric, then it takes 5-10 minutes for it to open up. other chokes open by a small tube that goes into the intake, drawing on the heat of the motor to heat the choke coil. that coil expands as it heats, whether electric or ambient, and as it expands, the tab rotates, pushing the choke plate open. the choke will stay open as long as the coil inside is warm enough. as the coil cools, that's when it begins to close.

 

[smartwork]

Re: 3.0 - what closes my choke?

...heat causing the choke to open.

By pushing the choke shaft tab?

... and the choke closes.

By what means? Gravity? Spring? The coil inside the choke only has a tab (no loop to go around the choke shaft tab), so it can only provide assistance in one direction (opening or closing it), so I'm trying to determine what provides the opposite action because there are no other springs on the choke shaft.

Maybe one other way of asking is: If I'm installing the choke coil and looking into the choke housing, which side of the coil tab should the choke shaft be on?

 

[ken_23434]

Re: 3.0 - what closes my choke?

If the coil pushes the choke open, what closes it? I don't see any spring on the carb or the diagram of the carb to close it, so if the coil cools the choke (as it is now) remains open.

The coil both opens and closes the choke. As described above, the spring or coil in the choke housing will expand or contract with temperature which causes the choke plate to reposition.

You could loosen the 3 screws on the cover to the choke and rotate the assembly to adjust the choke. If I remember correctly, rotating it clockwise (as you look at the cover) will cause the choke to be full open earlier. If you turn it enough, it will be full open at ambient temperature.

That should be enough info to get you into trouble.

 

[smartwork]

Re: 3.0 - what closes my choke?

The coil both opens and closes the choke.

For that to happen, the end of my coil needs a closed loop to go around the choke shaft's tab (else it can only move the tab in one direction). Mine doesn't have a closed loop... only a tab. Is that supposed to be a complete loop at the end?

 

[maxxman04]

Re: 3.0 - what closes my choke?

the choke plate is actuated by the choke rod. it's a combo of the weight of this rod, and attachment link, that "pull" the choke closed by weight. doesn't take much. then the coil tab engages tab for choke rod to push it open

 

[smartwork]

Re: 3.0 - what closes my choke?

the choke plate is actuated by the choke rod. it's a combo of the weight of this rod, and attachment link, that "pull" the choke closed by weight. doesn't take much. then the coil tab engages tab for choke rod to push it open

Thanks, Maxx. Although mine seems to move freely with the choke coil removed, the choke plate remains at any position you set it at (no auto-closing) but doesn't appear sticky or difficult to move. Is the closing by its own weight so sensitive it's simply not rolling due to the slightest build-up. I was expecting to see some type of assisted closing (like a spring on the shaft's end or linkage).

 

[maxxman04]

Re: 3.0 - what closes my choke?

when the motor is cold, there should be a slight bit of tension on choke plate, caused by the coil being contracted. and i must retract previous statement here, as it is the weight of the choke plate that pulls choke open. the choke closes as the coil cools, pulls it closed. if properly adjusted, engine cold, you should be able to push choke plate open, and upon release, it should spring back into close position. may not spring lightning fast or with a snap.

 

[smartwork]

Re: 3.0 - what closes my choke?

Bingo, Maxx! I was just coming back to report in case anyone else ran into the same thing. Although the shaft and plate appeared to move very freely, I just pulled them anyway for cleaning and it made a difference. It was then that I discovered that the shaft (rolls) holds the choke open using the process you stated. It then concluded that the coil then pushes the choke closed... not open. Everything was starting to click. I reassembled and it appears to function correctly. Nearly closed at cold (per my setting) and upon keyed power, fully open in about 30-60 seconds.

Thanks so much to everyone for their input. It's greatly appreciated.

 

[bayliner1996blue]

Re: 3.0 - what closes my choke?

I think I put my choke back togather wrong last night. I put the choke in the choke assemble with the tab mark (on the choke) at about the 3:00 position. I then rotated the choke counter clock wise and watched my choke close when the tab marks of the choke and housing were aligned. Under this configuration as the coil got hot (expanded) it would force the choke closed.

It must have not been working at all because as soon as I put the throttle at 1/4 (allowed the choke to move) it when full open. On a side note, my hot starts were much easier when the choke was non fuctional.

 

[smartwork]

Re: 3.0 - what closes my choke?

For reference, here's how I assembled mine. When you're staring into the side of the choke/carb with the coil assembly in your hand, the end tab of the coil went on the right side of the lever inside the choke housing. That lever is atttached to the choke shaft. Once the tab is on the right side of the lever and the coil is inserted into the housing, you can then rotate counter-clockwise as needed for adjustment. This way as the coil heats, it pulls the tab away (clockwise) from the lever and allows the choke plate to open using it's own weight & leverage on the shaft. As the coil cools, the tab pushes on the lever (counter-clockwise) and closes the choke. Note: The choke's shaft must be very freely moving. I thought mine was until I cleaned it and THEN it was free to move. If you have the coil removed, your choke plate (inside the carb opening) should easily fall completely open. If you reposition that plate with your fingers and let go, it should fall open. It should be moving that freely because that's what actually opens it. The coil doesn't open it... the coil "prevents" it from opening by pushing it closed to a varying degree depending on the temp of the coil.

Once the coil is inserted with the tab on the right side of the choke shaft lever, you can then rotate the coil (holding the outside housing of it) counter-clockwise and you should see your choke close. Once you adjust it to your preference, tighten down the three screws, you should be able to turn on the ignition and my choke fully opened (due to the coil heating up and relaxing its tension on the choke lever) in less than a minute or so. As we were discussing earlier in the thread, it's actually the weight of the choke plate (inside the carb), the linkage weight, and how it's attached to the horizontal shaft that makes the choke open (gravity and offset weight of the parts). The coil does not push it open. It pushes it closed, so when the choke is fully opened, the coil is warm, "retracted", and pushing at zero force on the choke's shaft.

That's how mine worked.

 

[bayliner1996blue]

Re: 3.0 - what closes my choke?

Just went outside to check the magic that is electic choke. IT turns out I assembled mine as you descibed so it was correct. I turned the key on (not starting the motor) and in about 1 min the choke was open. Now to focus on perfromance issues (see other thread).