Elect. Choke on 5.7L Merc - Where does pwr come from?

I have searched much and cannot find this problem.

I have a 1990 Bayliner 2650 Sunbridge with a 5.7L Merc I/O with 2 barrel carb with electric choke, (looks to be a rodchester carb).

The engine will start but then the choke continues to open all the way up and kill the engine. I can start it and jump to the carb and manually hold it back and keep the engine running fine but if I release, it opens all the way up and kills the engine even when it is fully warmed up.

Is there a sensor somewhere that controls the choke or is the electric coil just gone bad (because it does heat up and open the choke)? I have loosed the three screws and in a warm state, have to twist it almost 360 degrees to keep it running but if I leave it there the engine will never start cold.

Any help is very much appreciated.

Thanks and Sincerely,

Allen

Re: Elect. Choke on 5.7L Merc - Where does pwr come from?

Is the engine not warming up? The choke is supposed to stay open after the engine has been on and warmed.
I was looking at my wiring diagram and the electric choke is integral with the ignition, connecting at the alternator.
I think you may have other issues if the motor dies with the choke open and engine warmed up.

Re: Elect. Choke on 5.7L Merc - Where does pwr come from?

Hello RCSConstruction,

Once the engine does warm up I can keep it running at 2K or above but it will not idle unless I physically close the carb flap a little bit, then the engine runs good as long as I hold it there.

Does the iginition module control when and how much the choke opens?

Thanks for your post and any further info!

Re: Elect. Choke on 5.7L Merc - Where does pwr come from?

I agree. If the engine dies after the choke opens you have other problems. Your choke is apparently working like it should. It is closed when cold, and then the elec element heats up and opens the choke. By then the engine is warm enough that it doesn't need the choke... or at least shouldn't!

Re: Elect. Choke on 5.7L Merc - Where does pwr come from?

Fuel delivery or carb problem, there are threads on how to test.

Re: Elect. Choke on 5.7L Merc - Where does pwr come from?

I would bet money it is a vacuum leak.
Intake, carb base gasket, or vacuum hose.
You can test by spraying small spurts of carb cleaner around suspect area's and if the engine rev's you found your leak.
Let us know what you find.
edit--
Possibly a stuck/gummed up PCV valve?

Re: Elect. Choke on 5.7L Merc - Where does pwr come from?

Thanks Gentlemen,

Good info, I will check and get back to you all.