Electric choke. I need a brief explanation please

[djcamera]

Mercury 75HP made in 1986. The electric choke is a solenoid that magnetically draws up a little steel plunger linked to the butterflies. In trying to figure out why it's acting intermittantly, I want to trigger it with a remote button, the way I often jump other solenoids, like the starter or T/T. Weirdly, it only has one lead (yellow/black wire) going to it, and it's straight from the wiring harness. Is it grounded by the bolts attaching it to the block? How else would it be grounded?

And how can I test this solenoid to see if it's good? I want to "CLICK" it other than with the push-key. Replacing it is doable, but man, it will be a pain. The flywheel has to come off, the entire cowling, etc.

 

[racerone]

Is this the 4 cylinder ?-----Serial # of this motor ?--------Why do you say that the flywheel needs to come off ?----Why would it be " weird " that it only has 1 wire ???

 

[djcamera]

4 cylinder, yes. No serial # on my at the moment, but here's the parts list: https://www.perfprotech.com/mercury-marine-parts-catalog/umodel/25809

And the solenoid drops down into its bracket in such a way that the flywheel would have to be removed to remove/replace it. As for the one wire, I believe every 12V part I've ever wired up has a lead and a ground. All my other solenoids are that way. I just found it odd. I imagine the mounting bolts ground it, but hey, I'm dumb. So all help appreciated.

 

[fastjeff]

I believe that's an enrichener device, not a "choke'. If so, it causes a deliberate flooding of gas into the motor to promote cold starting. Energizing it opens a valve that leaks gas in the system directly into the motor.

Jeff

 

[racerone]

BUT -----He says it has a plunger linked to the choke butterflies on his motor !!

 

[djcamera]

 

[haventaclue]

I'm thinking,as you say this wire is coming straight from the harness,the wrong wire is connected to your choke.Look for a grey wire.Check where that yellow is coming from,I'm guessing from under the flywheel.

 

[fastjeff]

Missed that. sorry.

That's the Mercarb carb enrichment system. Assuming the linkage is operating correctly, then the tiny passages inside the carb may be plugged. That's a common problem with these since ethanol gas arrived to rot the inside of the fuel hoses (and deposit tiny black particles in the carb).


I have a fix for that.

Jeff

 

[faztbullet]

Very easy fix DJ...The solenoid base is grounded thru the cowling support..just like your starter as it has no built in ground wire. Those solenoids get weak over time due to heat from setting in sun over the years. Make sure plunger is not rubbing on any wires and if free ...remove solenoid, add 2 thin 1/4-20 S/S washers under the solenoid base (red lines) to shim it down and reinstall. Gives magnet field more area to grab on plunger..

 

[haventaclue]

Not often I disagree with you Jeff,but shouldn't there be two wires,yellow/black and black coming out of the enrichment module? I wonder if there has been some chopping and changing to the motor.To my eye that is a magnetic electric energized choke. I think the serial number is needed

 

[racerone]

Some of the newer ones use that solenoid to operate VALVES on the carburetors and NOT choke plates.----Without clear pictures or a serial # folks get not expect clear answers.

 

[djcamera]

Very easy fix DJ...The solenoid base is grounded thru the cowling support..just like your starter as it has no built in ground wire. Those solenoids get weak over time due to heat from setting in sun over the years. Make sure plunger is not rubbing on any wires and if free ...remove solenoid, add 2 thin 1/4-20 S/S washers under the solenoid base (red lines) to shim it down and reinstall. Gives magnet field more area to grab on plunger..
View attachment 22891

Now THAT'S the answer about the ground & wire I was looking for. Thank you, sir. Makes perfect sense. The motor is my winter project and was sitting for years in the weather, and this choke solenoid is one of few things I didn't replace or verify its condition. It's been working intermittently, so perhaps the ground contacts have some gunk or the plunger needs a cleaning or some WD-40 or maybe something is touching the plastic link. Thanks for the help.

 

[djcamera]

You're right. It's an electric choke, like I originally said. This motor does not have an enrichment module.

 

[racerone]

dj----Do the carburetors on your motor have---- CHOKE PLATES ----Yes or no ?

 

[fastjeff]

"Inquiring minds want to know."

First thing to do (to reduce some of this confusion) is to see if the object the solenoid is supposed to move, moves all the way as planned.


If it doesn't mess with it (bad ground, bad solenoid, etc.) until it does.

If it does move all the way, let us know and we'll go on from there.

Everyone wash your hands!

Jeff

 

[djcamera]

Sucessful resolution: it was 100% a bad solenoid. Swapped out from my cannibal/parts motor and we're click-click-clicking nicely now.

 

[BarG]

Congratulations dj! NOW tell me you did not have to remove the fly wheel!. I also have an 1986 Merc (Classic Fifty) and I am going to put on a new choke and it seem that if I could disconnect the butterfly linkage, I could remove the choke Without even removing the cowling support, if not I would have to pull the cowling support in order to get the linkage disconnected and re hooked to the new choke. Did you remove your flywheel??