Carbon fouling, all plugs

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Aug 20, 2021
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Cornelius, NC
77 been running perfectly, started to miss and smoke after a 4 mile drive. All plugs are carbon fouled, just tuned up a 100 miles or so ago. Oil looks good, coolant good, compression test tomorrow but think it's carb related? What to do to start diagnosis?
 
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Cornelius, NC
Yeah, air filter looks okay, replacing today just for the fun of it. Think it's factory pump. It ran great, maybe a bit rich at idle (I could smell it) but all of a sudden it started running like hell as I got to my neighborhood, not a gradual thing, almost felt like it was running with choke on but it is disengaged.
 
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I don't think I'm going to do a compression yet, the fact that all plugs are fouled and it ran too good even a day ago. sure feels like over fueling but I have little experience with carbs.
 
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If you're running a stock Aisan carb, then you should have a look at the fuel level in the sight glass. Start it up for a minute and then shut it off and check the level, should be around half way up the glass. If it's higher than that, you probably have a stuck needle valve and will be running rich.
 
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Cornelius, NC
If you're running a stock Aisan carb, then you should have a look at the fuel level in the sight glass. Start it up for a minute and then shut it off and check the level, should be around half way up the glass. If it's higher than that, you probably have a stuck needle valve and will be running rich.
This car has run very little the past 5 years after a rebuild/restore. Think i need to rebuild carb for piece of mind anyway, is it doable or better to send to Mark offroad?
 

Pighead

Stop calling it an FJ
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All plugs? I might check the inside of the dizzy cap and rotor, clean those up.
 
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Cornelius, NC
So, cleaned the plugs and started right up. Still have plans to rebuild carb but what is happening is while driving the choke circuit somehow becomes engaged. Happened a minute ago again. I can pump the gas pedal a few times and it releases. My choke pull is firm and all the linkage looks okay, any ideas as to what is causing this to happen?
 

Pighead

Stop calling it an FJ
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No idea at all. But that is some complicated linkage that still stumps me as to how it all exactly works.
A liberal dousing with carb cleaner never hurts, followed by the lubricant of your choice
 

Dizzy

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Santa Fe, New Mexico
77 been running perfectly, started to miss and smoke after a 4 mile drive. All plugs are carbon fouled, just tuned up a 100 miles or so ago. Oil looks good, coolant good, compression test tomorrow but think it's carb related? What to do to start diagnosis?
Burnt oil? I'd bet that they are just a tad shiny, not fluffy and flat-black suit, hence, oil. Post pics, please. Is this engine/carb hooked up to the EGR?

The only two ways that I could make my original '75 carb run rich is by disconnecting the vacuum source to the power valve (knew it because of the bad economy at the gas pump), and having incorrect float settings. The choke may have done it too.
 
Joined
Aug 20, 2021
Messages
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Cornelius, NC
Burnt oil? I'd bet that they are just a tad shiny, not fluffy and flat-black suit, hence, oil. Post pics, please. Is this engine/carb hooked up to the EGR?

The only two ways that I could make my original '75 carb run rich is by disconnecting the vacuum source to the power valve (knew it because of the bad economy at the gas pump), and having incorrect float settings. The choke may have done it too.
No oil, flat black carbon, completely dry plugs, I'll get pics later if they are still fouled. Egr not hooked up.
 

roadstr6

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Is there a paper gasket between your carb and the bakelite insulator below? If so, remove the air cleaner assembly and look down into the carb to make sure your secondary butterfly is not snagged on the paper gasket. I have had this happen to me. Secondary opens up, gets hung on the gasket and can't fully close. When that happens, your carb pulls fuel around the idle circuit and runs super rich. If you have a paper gasket, trim it back so it can't contact the secondary butterfly or consider removing it altogether. You shouldn't really need it if your insulator is not buggered up. Mr. T did not intend for there to be a gasket.
 

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