1990 Toyota Corolla Carb setup

JACKOLSON

MEMBER
1990 TOYOTA COROLLA
4 CYL
FWD
MANUAL
80,000 MILES

Hi guys,

How do I set the fuel mixture with my carb?

Thanks,
More power
Jack

Tuesday, July 21st, 2009 AT 4:14 AM

6 Replies

MHPAUTOS

MECHANIC
31,937 POSTS

Hi there,

I am presuming that you have no access to an exhaust gas analyzer, the old school method of getting the mixture approx correct is making sure that all the other tune items are ok first, warm the engine and set the idle as best you can, set the mixture about 1 1/2 turns in, screw in until it evens out the idle, screw further in until it starts to run rough, back it off un till it smooths out again, that is about as close as you will get it with out an analyzer, if this dose not work there will be a problem in the carby or a vacuum leak somewhere.

Mark (mhpautos)

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Tuesday, July 21st, 2009 AT 6:08 AM

JACKOLSON

MEMBER
67 POSTS

Thanks so much.

Yup I don't have an analyzer but if I can get one, what should I do?

Okay, I've set my car to 800rpm using the needle valve, the one you can turn by your fingers. So after that I have to screw in the other needle valve? The one beside it, almost, that you can only turn with a screwdriver. Am I on the right track?

Where do I have to look for vacuum leaks? Seems everything's okay but I want to know for sure. The "aircon" guy must have messed up the actuators before or something, or I don't know, do I have to change my fuel pump?

Sorry for the lots of questions, I just want to do my car by myself because I don't really trust the mechanics here in my area.

More power,
Jack

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Tuesday, July 21st, 2009 AT 8:22 PM

MHPAUTOS

MECHANIC
31,937 POSTS

Hi there,

Yes the large screw with the knob is the idle, the mixture screw is the other one, you will have to do a visual check on all the vacuum hoses, check that they are not split or loose, if the car is running the fuel pump should be ok, what is your exact problem,

mark (mhpautos)

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Tuesday, July 21st, 2009 AT 9:39 PM

JACKOLSON

MEMBER
67 POSTS

Thanks Mark,

Well, right now, the problem is that I don't think my car is generating the full power it can make.

Symptoms:
1. When I accelerate very aggressively, it misfires, somewhat, or knocks, I can't really tell which.
2. After a cold overnight parking, when I start the engine, the rpm sets to about just 500rpm which is supposed to be higher during cold starts then it would settle to 800rpm.
3. Even in the middle of driving, when I pull over, the rpm would sometimes drop to 500. I would have to bleep the gas then it will settle back to 800.

These things annoy me, but, the car runs fast, can still do 170kph @ 4000rpm, the revs are good most of the times, new oil, new gear oil, new clutch, new brakes, new sparks and wires, timing set to 10degrees before TDC.

Ei, thanks for the support, more power!
Jack

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Friday, July 24th, 2009 AT 8:46 PM

MHPAUTOS

MECHANIC
31,937 POSTS

Hi there,

these engines are really not made to be pushed so hard, you will through a rd at that engine load, the coil and leads are more than likely breaking down, they are not made to sustain that sort of pressure, You will need to re set the choke fast idle, this will determine the cold idle speed.

Mark (mhpautos)