70 HP Johnson Plug fouling

[eclark53520]

70el77 model

This motor has a solenoid choke.

From looking at it, after choking most times the choke doesn't shut all the way(or at least it doesn't close 100%, i can shut it further than it closes by itself).

Could this be causing a rich condition and fouling the plugs?

I'm not sure how far down the linkages have to go to open the choke completely. Maybe there is some play, and this is fine.

 

[Daviet]

Re: 70 HP Johnson Plug fouling

The choke plates should shut all the way when you activate the choke. If the engine starts ok when cold leave it alone.
The choke is not involved in the fuel mixture, except when choking a cold engine, if the plugs are fouling out and the choke plates are completely open, your problem lies elsewhere.

 

[jtexas]

Re: 70 HP Johnson Plug fouling

If the choke plates don't stay 100% open, the choke solenoid itself can be moved back from the carb linkage by loosening the retaining clamp. If you make this adjustment, you have to make sure it still closes 100% when the choke is engaged.

Or the spring linking the plunger to the carb, it might be sprung and ready for replacement.

"I'm not sure how far down the linkages have to go to open the choke completely. ..."
Sounds like maybe you're just looking at the linkage -- if so, you have to take the air silencer cover off to observe the choke plates.

"Maybe there is some play, and this is fine."
Nope, no room for play -- you need 100% choke for cold start, and 0% choke at all other times.

 

[eclark53520]

Re: 70 HP Johnson Plug fouling

I notice now that my terminology was incorrect.

When i was saying it doesn't close all the way, i meant to say the choke wasn't opening all the way.

When the choke is activated, the linkage goes all the way to the stop. When i let off the choke, the linkage does not go all the way to the other stop point.

So in summary, the plates are 100% closed when i am choking the engine. The linkage does not go all the way to the stop when i let off the choke, i do not know how that correlates tot he actual plates in the carbs because i cannot see them.

I should just take the arrestor off and see, but they put a screw in a place where i'm not sure how to get it out, i'll need to pick up a swivel socket at least and possibly another universal to be able to get a ratchet on it.

Thanks for the replies guys. So if the choke plates do not stay 100% open during run time, that can cause me to foul plugs right?

 

[Daviet]

Re: 70 HP Johnson Plug fouling

Correct, if the choke is not opening up all the way it could affect the running of the engine and foul spark plugs.

 

[eclark53520]

Re: 70 HP Johnson Plug fouling

Correct, if the choke is not opening up all the way it could affect the running of the engine and foul spark plugs.

Thanks!

 

[Daviet]

Re: 70 HP Johnson Plug fouling

You're welcome, let us know if adjusting the choke plates helps your problem.

 

[eclark53520]

Re: 70 HP Johnson Plug fouling

Will do, i'm going to adjust tonight, however, i won't be able to run it in the lake till Saturday. Hopefully i'll have good news then.

 

[jtexas]

Re: 70 HP Johnson Plug fouling

...
I should just take the arrestor off and see, but they put a screw in a place where i'm not sure how to get it out, i'll need to pick up a swivel socket at least and possibly another universal to be able to get a ratchet on it.
...

You're talkin bout the bottom screw on the port side, or maybe one of the other two on the bottom give you more trouble? no matter, they're all the same.

I tried every tool in the box on those air silencer cover screws, and what works best is, put a nut driver on it, push in and down with as much force as it takes to get a grip on it, and man-handle it on out. It's not going to break.

Wonder what everybody else uses?

 

[Daviet]

Re: 70 HP Johnson Plug fouling

I use a 1/4" flex socket that I ground down to make it as short as possiable and still be able to grab the head of the bolt, back it out a couple of turns and then you can use a wrench on it.

 

[eclark53520]

Re: 70 HP Johnson Plug fouling

I have an old rusty broken 1/4" ratchet, i thought about tearing it apart and using the drive square part welded to a small steel bar that i could bed to clear the arrestor.

That would allow me to get a socket on it, its thin enough to fit between the lower case and the screw, and handy enough to keep around the garage for the next time.

 

[eclark53520]

Re: 70 HP Johnson Plug fouling

Alright...i figured out what was going on.

There is a wire thats wrapped around the throttle shaft of the middle carb right behind the plate that hooks up to the throttle linkage. This wire was holding the choke plates a touch closed while at idle, but i noticed as soon as you move the throttle, this wire moves and the choke linkage drops down to 100% open.

Then as i went further i realized that the same wire that was holding the choke a bit closed at idle was holding the choke 100% open while at WOT, presumably so it doesn't bounce shut while operating on rough water.

I'm pretty sure thats not the issue.

I have come to the conclusion that the fouling problem was being caused by old fuel. The guy i bought it from still had gas in the tank from when he bought it 3 years prior. So far, I've had it in the water 3 times and never had a problem fouling plugs like he did. New gas, problem solved thus far.


Thanks for all the help everyone!