Electric choke not opening up

mark1905

mark1905

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I thought that I had fixed my choke problem, but apparently not.


Choke snaps shut on cold startup, but won't open again until fully under way. Idle zone out of the marina is full of black smoke and chugging. Once I've got WOT, she's fine for the rest of the day.. even if I shut it off and start again. It's just the first start-up.

Linkage is fine, wires are fine, everything sitting as it should and/or was when it has been working fine for the last few years.


Where/what should I be checking?
 
Bt Doctur

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Re: Electric choke not opening up

loosen the adjusting screws and adjust with the engine cold so that it closes on a 1/8 th inch drill bit
 
mark1905

mark1905

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Re: Electric choke not opening up

Alright..

Pulled the flame arrestor off and inspected the choke operation. What's happening is that the metal coil is intermittently not heating up fast enough and opening the choke. It will open about 1/3.. but then just stay there until I run at WOT for a while and I'm assuming the heat from the engine finally warms the coil up enough to fully retract the choke. Choke is adjusted correctly.. that's definitely not the problem. It's getting the coil to heat and retract..

I'm assuming that I should be seeing +12v at the purple choke wire with the ignition on, correct? If I'm seeing those +12v and the coil is not heating and retracting, then replace the coil assembly? FWIW, I've already checked and can't locate where they sell just that coil/plate piece separately..

On the flip side, anyone ever just remove the choke?
 
Bondo

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Re: Electric choke not opening up

I'm assuming that I should be seeing +12v at the purple choke wire with the ignition on, correct? If I'm seeing those +12v and the coil is not heating and retracting, then replace the coil assembly?
Click to expand...

Yes.....
On the flip side, anyone ever just remove the choke?
Click to expand...

Ayuh,... I guess ya could, but cold starts won't work so well...
 
mark1905

mark1905

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Re: Electric choke not opening up

Just ran outside and put a voltmeter on it. +8.8v at the purple wire, and the battery is fully charged and reading +12.5v. Not the ground wire, either.. tested straight to battery ground.

Now to try and trace that wire.. any insight?
 
Don S

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Re: Electric choke not opening up

First, how are you checking the voltage. You need to hook your negative test lead to a good ground and leave it there. Then turn the key to run and check voltage on the + terminal of the choke coil (purple wire) also check the purple wire on the coil and see if they are the same.
If you are using the meter on the + and - terminals of the choke coil, you are reading the voltage drop across the resistance, not the voltage to the choke coil.
 
mark1905

mark1905

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Re: Electric choke not opening up

I put the GND lead of the meter directly to the battery terminal, unhooked the purple wire and tested it directly which gave me a reading of +8.8V. I checked battery voltage directly at the terminals and it read +12.35V. Put the meter to the GND wire on the choke and the purple wire and it too gave me a reading of +8.8V.

You're saying that the switched power for the choke actually originates at the coil?
 
Don S

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Re: Electric choke not opening up

You're saying that the switched power for the choke actually originates at the coil?
Click to expand...

I was just trying to determine where the problem might be, I'm including the wiring diagram for your engine. There is a connection where 5 purple wires are connected together in the wiring harness. I was looking to see if it was that way to other items as well. (alternator, shift interrupt, choke, ign. coil, and the purple wire coming from the ign. sw..
 

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mark1905

mark1905

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Re: Electric choke not opening up

Ahhh haaaaaaaa... so all those purple wires are together! Interesting. I'm going to go poke around see what the V is on the shift interrupt wire, etc.. trace it back and see if somehow where they all connect may be corroded..
 
Bondo

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Re: Electric choke not opening up

mark1905 said:
Ahhh haaaaaaaa... so all those purple wires are together! Interesting. I'm going to go poke around see what the V is on the shift interrupt wire, etc.. trace it back and see if somehow where they all connect may be corroded..
Click to expand...

Ayuh,... All those purple wires are powered up by the keyswitch,...

It's the Ignition circuit...
 
F

fkboatman

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Re: Electric choke not opening up

better make sure its not a resisted wire going to choke stat, it will not open at proper rate and load motor up or it may not open at all.
 
Don S

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Re: Electric choke not opening up

fkboatman said:
better make sure its not a resisted wire going to choke stat, it will not open at proper rate and load motor up or it may not open at all.
Click to expand...

Merc does not use resistor wires going to the choke :facepalm:
 
NHGuy

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Re: Electric choke not opening up

FWIW, I've already checked and can't locate where they sell just that coil/plate piece separately.. look here, http://www.iboats.com/Mercruiser-Ch...1512358--**********.270258925--view_id.269569

On the flip side, anyone ever just remove the choke? I tried that, boat runs crappy til warm that way too.

I don't have the tech info on your voltage. If you have a resisted ignition system it may be normal.
 
mark1905

mark1905

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Re: Electric choke not opening up

NHGuy said:
I don't have the tech info on your voltage. If you have a resisted ignition system it may be normal.
Click to expand...

If you check Don's facepalm above, he states that Merc doesn't use resisted ignition wires.. it's either 12V+ or it's not. You can see from the diagram posted/attached that the coil, ignition interrupt, choke coil, etc.. all get the same 12V+ from the main purple ignition wire coming off of the main harness.

It has to be corrosion. I've dealt with tons of it on this boat being as that it lived the first 2/3 of it's life in a salt environment over in Tampa..]


Very nice link for the replacement choke! I swear that I searched and never saw them sold separately. I found it for $25 vs $90 on Ebay though.. http://www.ebay.com/itm/2bbl-Mercru...Parts_Accessories&vxp=mtr&hash=item43ac460869
 
F

fkboatman

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Re: Electric choke not opening up

I know merc does not use a resistor on there newer engines. did not see that it was o 97 3.0 at the bottom of his post. my bad.
 
Don S

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Re: Electric choke not opening up

fkboatman said:
I know merc does not use a resistor on there newer engines. did not see that it was o 97 3.0 at the bottom of his post. my bad.
Click to expand...

Merc has NEVER used a resistor wire to the choke coil, on old engines with points, there was a resister wire going to the ignition coil, but it did not go to the choke.
 
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