wheres the mix adjust on a nikki?

My haynes manual is a real help in this it says nothing about the carbs but if you have fi well you got all the info.

So yeah if anyone knows where it is my truck is putting out carbon when revved in neutral and is now getting 290km to 48L, basicly a full tank but the cel isn't on and it starts, runs/idles awesome you almost cant tell its running even with the stereo and fan off. So I think the it may just need an adjustment (or a new carb/fi setup)

There is no manual mixture adjustment on the nikki carb.
The mixture is computer controlled thru the mixture control solenoid inside the carb.
When the stock carb starts failing, the gas mileage drops dramatically becasue the mixture control fails to open position.
The remedy is to rebuild the carb by replacing the mixture control valve or just simply replace with a Weber.
If you have emissions testing, you don't have any choice but go back to the stock carb.

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I have a digi multimeter but i dunno if it does dwell (never had to use it for anything but voltage) it passed emissions with flyin colours 2 months before the mileage went in the toilet due to how it was done it can be good for 4 years. Can a weber not be tuned to operate with acceptable emissions? It looks like the prev owner fooled with it before, it was doing awesome when i got it. I dunno how much more i want to put into this truck cause i'm graduating and have a great job lined up so i'm lookin at a 98-04 b3000 probably (i know i said i don't like the shifter a few times but meh)

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i did the above tests (except the vaccum one) and the voltage from the senor was at idle .67V and lowers when revved was .44V (.08V with engine off), it didnt respond to the tests involving the computer and solenoid the idle stayed the same.

prior to me buying it it sat for a couple months it got awesome mileage and etested really well when i first got it 2 months later i changed the oil, plugs
(properly gapped), wires, cap rotor, coil, cat and front piping, air and fuel filters cleaned the carb with carb cleaner, ran an in the fuel cleaner through that was approved for carbs.

it runs way smoother and more powerfully than before but the mileage dropped from 27mpg hwy to 19mpg hwy.

sound like i need a new carb/comp?

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the cab gets warm eventually, faster since i covered 1/2 the rad with cardboard it reads about 1/2 way on the heat gauge when warm.

i just did a hwy trip of 70km and averaged 12.5 mpg in heavy snow at 120kph but 20mpg on the return when it wasnt soo windy both times the truck was warm it's too hot with the heat on full in -20C weather.

i've pulled the pcv out with the eng running and it didn't stall but the pvc is before the carb so it wouldn't make it lean right? it has 190000km on it.

i know a retired mechanic and he said you can often use carb cleaner and clean an oxy sensor

there was no change in voltage with a vaccum leak (i tried many vaccum lines) it was 0.55 normaly and went down to 0.08 when revved but like i said today it got decent mileage. it makes alot of black/brown watery crap from the exhaust when it first started today i revved it and it made a huge black/brown cloud then eventualy made white (-20C outside)

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i didn't try the brake booster but i tried the smaller lines like chaecoal canister etc. the butterfly opens properly

with the pcv hose removed it revvs way up at high idle but at low idle it dies

havn't had a chance to try the coolant temp switch cause its really cold out right now i'll look at the coolant tommowwor when i can get it in the garage at work we do rad flushes theere so if thats what it is then i can fix it there.