rough idle black smoke
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rough idle black smoke
I got a 86 351 4V, that was running good until recently. It has developed a rough idle, with alot of black smoke. Ive checked for fuel dripping when idling,dosnt drip.Checked the float levels. The front bowl is just below the hole,the rear bowl isnt right up to the hole, but is maybe a quarter inch below. I did nothing to the idle adjustment hex heads, because it ran fine before. Another thread I looked at refrenced a power valve problem. ANY IDEAS WOULD HELPFUL, THANKS
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rough idle
The choke plate does open as the motor wama up. when I insralled this motor, and firstgot it running it acted the same way, until I noticed the elect. choke wire was off. The wire was attached, and I noticed something in the choke mechanizmn,move then it smoothed out.Ran good for a few weeksof test driving,until recently developed the rich condition. If revved upit clears, and doesnt have the loping sound of a lumpy cam.
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From: Virginia
The diaphragm gets a hole in it, and leaks gas through, and also doesn't pull the brass valve part closed. Sometimes you can push on the brass valve and then hold your thumb over the opening on the diaphragm and see if it leaks down. You could also put something like wd40 on the diaphragm side and see if it leaks through to the other side.
Engine vacuum is put on the diaphragm, and that pulls the brass part closed. When you are pulling a hill and have the gas pedal down pretty good, the engine vacuum drops, and this lets the spring on the brass part, push the brass valve off the seat and lets extra fuel into the engine. That's why it's called a power valve, it adds more fuel according to engine load.
Engine vacuum is put on the diaphragm, and that pulls the brass part closed. When you are pulling a hill and have the gas pedal down pretty good, the engine vacuum drops, and this lets the spring on the brass part, push the brass valve off the seat and lets extra fuel into the engine. That's why it's called a power valve, it adds more fuel according to engine load.
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Thanks for all of the inputs, every body. The mechanic is real busy, that I usually bring my stuff to when Im about ready to give up. Im going to operate today. Will repost results. THANKS AGAIN
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ROGH IDLE BLACK SMOKE WONT START
OK Now it wont start. Getting alot of gas. Checed the oil and found it to be overfull, so I drained it,and removed the filter. Going to get oil and filter tommorrow and try again.
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Hopefuly itll run tommorrow. Should I attempt to start it, or should I go ahead and take the front off to replace the power valve. I dont really knowhow this works but, Im one heck of a parts changer.LOL Thanks I rmember he first carb I tookapart was a quadrajet on my 68 chevelle them needle things were all bent to shjt.,bythe time I got donewithit.
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Flooding condition
I changed the oil , filter ,still wont start. It did fire a coupe times. When I Crawled up and opened the choke, and throttle, I could see gas pooled inthe phlenm. Took the fuelline off,then removed the bowl,the metering block. The float appeaed to be ok the needle not hangingup, the acceeratof pump squirted fuel out of a small hole. I REALLY DONT NO WHAT TO DO NEXT. This carb has been remaned,looks like new stickers and all. HELP.
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