so say you pick up random yota car with a carb that was last driven.... well it drove to where they parked it, and they never drove it or have been "fixing" it for a couple moons. it will prolly look something like this not very pretty is it? a crap ton of aged rubber prolly cloged with carbon and old gas. this can affect everything from first start to dieseling after shut off. expect to spend at least a couple hours playing with it. but afterwards you wont believe how well it runs. first lets start with removing the air filter and fuel line. next pull the 2 drain plugs off the front of the carb. they are the "covers" for #33/34 now that you've drained all the gas out of the carb, you should do the same for the tank. to prevent future issues. pump the throttle a few times to get any gas out of the power valve. replace both plugs. now start spraying carb clean EVERYWHERE, mind the dog. start in the throat (the big hole on top) and start with the tiniest holes you can see. spray em out good. then work your way up to the 2 tubes at the very top. spend a lot of time on the two idle jets, they are inside the small vertical tubes in the throat. one is hidden by the choke plate, you will have to use a crazy monkey death grip to hold it open and get the lil red tube where you want it. i really am sorry my camera sucks. now the 2 tubes slanting towards the front of the carb are vents. you want to FILL the carb with carb clean through these tubes. once its starts dripping out of the gas inlet you disconnected earlier you know you have enuff. pump the throttle a bit till you see carb clean come out in the throat. now the time consuming part. start with 15ft or better of new vacuum line. the best way to find out what size is to bring a example into the parts store. ONLY REMOVE 1 LINE AT A TIME EVERRRRR!!!1! now replace each and every vac line you can find. including the brake and pcv lines one at a time. as you take off a line make sure the fitting is clear and not clogged with carbon. dont stick anything in there, use carb clean or compressed air followed by carb clean on trouble spots. now after you've finished replacing all the vacuum lines, go and resrpay every port or lil hole you sprayed eariler with carb clean starting in the throat.. then pull the drain plugs again, yes both of them. spray again with carb clean to wash out any bigger particles hanging out inside. then follow up with compressed air. be careful with compressed air on and diaphram fittings, better to let them air dry. speaking of air drying, let the carb air out for a bit with out the drain plugs in, like go have a beer. now replace the plugs, the fuel line, and the air filter. turn the key to "ON" and let the carb fill with gas, you can watch the sight glass on the front of the carb. onece the carb has gas pump the throttle a few times and start the car. might run kinda rough for a sec but will clear up. i also reccomend running a bottle of redline fuel system treatment through the car. add it when empty and fill up. by half a tank you will see a difference.
I remember reading this last year. Did it to my carburetor today. Tremendously helpful. An old posting well worth bringing to the forefront once again.
your idle adjustment screw is on the back of the carb, near where the throttle cable goes round your little ramp to actuate the throttle. You might need to loosen it until your idle drops. Also check your timing. If your timing is too advanced, it will idle high. timing alone won't make it go to 2k, but it might be a contributing factor.
on my set of mikuni 40's, the air mixture screw is coming all the way out with no change in engine idle, anyone have any advice? i set my idle screws to where its lightly seated on the idle plate, and backed out all four mixture screws four rotations. it seemed the motor ran the roughest on the first three rotations for the mixture screws but didnt notice any change after....?
Below is from Weber IDF tuning info...... If your mixture screw is out more than one turn like 11/2 turns then your idle jet is too lean, go up one half size on the Idle jet. If you mixture screw is not out one full turn, something like only 1/2 turn out from seated then your Idle jet is too rich, go down one half size on the idle jet.
so im having to turn my mixtures out about 4 times to get the motor to sound right....i guess i need to increase jetting size? thanks brother, im learning as i go!
I just replaced the stock carb in my 87 pickup with a rebuilt stock 2 barrel. Its been idling oddly and I've been trying to figure out why. This post gave me a few things to try. My next move was to start replacing everything connected to it. After reading this i think I'll start with all the vacuum lines. Thanks.
