Choke solenoid plunger not dropping back down. 1967 Merc 650SS

[tgp***]

Choke solenoid engages when I press the choke button but solenoid does not come back down and keeps the choke door closed. Spring operates the choke flap on the carbs just fine when I close it by hand, opens back up immediately when I let go. I'm baffled. Any ideas??

 

[emckelvy]

Are you sure that the choke solenoid is de-energizing after you release the choke button? Maybe the button isn't releasing properly.

Any grease on the choke solenoid plunger, that'll cause it to stick.

You may need to remove the plunger and check its fit into the choke solenoid. It may have a burr on it that's causing it to bind.

Note that while grease will cause the plunger to stick in the solenoid, a little light lube such as WD or 3-In-1 won't hurt.

Make sure the choke solenoid pivot point isn't hanging up, as well.

Last thought, when you pull up on the manual choke, it won't make the plunger go as far up in the solenoid as magnetism will pull the plunger when the solenoid is energized. So it might be a case of binding at the plunger's extreme of travel.

HTH...........ed

 

[tgp***]

Thanks emckely,

I was working on it yesterday, removed the plunger from the solenoid, did not appear to be hanging up, just the WD from which I sprayed in earlier was inside (as that was my first thought.

I'll have to check de-energizing. Not sure exactly how to do that. Removing one of the wires would make sense to de-energize. Or just disconnecting the battery should do the same thing. Not sure how that works on a solenoid. Not de-energizing would make sense as I have to push down on the linkage to have the plunger come back down. However, if it was still energized, it does not go back up if when I let go, it stays down until I press the choke button again and it goes back up like it should.

Linkage. I'll look at it again, but appeared fine.

So am I correct in saying that spring on the linkage does not pull the choke back down. Only acts as a return for the choke door flap?

Thanks again for the response.

 

[emckelvy]

So am I correct in saying that spring on the linkage does not pull the choke back down. Only acts as a return for the choke door flap?

Thanks again for the response.

Well, the spring would tend to pull the entire choke assembly downwards, along with gravity. Note that if the choke shutters are too tight, they might tend to bind, and even though you could get them to open by pushing down on the manual choke, they might not return when you're running the electric choke. You can change the tension on each choke shutter via the self-locking nut which holds the shutter to the carb. Just don't get the shutters too loose, or they won't seal against the carb and you'll get little choke action.

It does sound like your choke switch is working ok. You could always put a meter or test lite at the solenoid connection to be sure power goes out when you release the button.

All the solenoid is, is a whole bunch of windings of fine wire, one end of which is grounded to the metal case of the solenoid. When power is applied to the wire terminal on the solenoid, the coils are energized and become a strong electro-magnet, pulling the plunger up into the solenoid. When you release the choke button, the solenoid is de-energized, releasing the plunger, and the choke shutters return to the open position.

But it seems to be more of a problem with either the choke plunger hanging up inside the solenoid, or binding choke shutters............ed

p.s. after-thought, the choke return spring is actually quite strong, and as soon as the choke solenoid is de-energized, the spring should cause the shutters to snap open. Maybe post a pic of your choke linkage.

 

[GA_Boater]

The return spring is strong. I had trouble with the two pivot screws being too tight and caused the same trouble. I want to say that I might have put one more wrap on the spring, but that's a hazy memory. The tight screws for sure.

 

[gm280]

I would think that IF the choke was staying energized, that you would feel a little warmth on the choke solenoid after a little time. I don't think that is the problem, I lean towards it sticking... JMHO!

 

[tgp***]

Thanks Guys, the spring opens those shutters when the solenoid is NOT in gauged. I can test by loosing the nuts to see if the too tight. I thinking its not de-energizing, I will see if I can borrow a meter to test it too.

Thanks again for the help. I may have more questions when it comes time to test it. It will have to sit for a little while as I'll be busy with work. Stay tuned I'll keep you informed next time I work on it.

Thanks again.

 

[GA_Boater]

When you get back on it, disconnect the wire to the E choke. I think on yours it goes to a small terminal strip between the fuel pump and starter, mounted on the block. If it's staying energized, it should drop when the wire is unhooked.

I looked at mine this afternoon and I don't have a spiral spring like the parts diagram. I have a long coil spring similar to many older cars. So I don't know what spring I was talking about in post #5. :noidea:

Do the choke flaps open and close completely using the manual choke? Part #13, the screw/bolt holding the "U" link to the choke knob is really long. If it isn't fully into the choke knob shaft, all kinds of funky choke things happen.