Mechanics

STALLING AND LIMITED SPEED

1979 Mitsubishi Lancer • 78,000 miles

Help me please : (
i'm new here. Im new at cars. I got mine last march
a used mitsubishi lancer colt.
and i'm wondering if someone could help me with my problem.
it runs at most 60 when cold and 80 when the weather is hot.
and it does a quick uhm. Not really a stall. But not strong enough to be a misfire. I don't know what it's called but there's an air burst on my air cleaner

there's this second barrel on my carburetor that's got a double butterfly and the butterfly below opens at 80% throttle but the top one wont budge. Is it normal?
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Jicary
June 4, 2012.




Don't quite understand your problem-check the choke plate adjustment/carb linkages


Tiny
Rasmataz
Jun 4, 2012.
The secondary throttle is not opening and it could be stuck/seized or the vacuum (if equipped) is leaking.

With engine off, turn throttle fully opened and try moving the secondary throttle to see if it moves freely.


KHLow2008
Jun 4, 2012.
Sorry. It's confusing, is it.
Even i'm confused. Let me try to draw it.
Nothing is stuck. But the top butterfly is not opening.

Uhmm. This is how I see it.
The main throttle is playing properly. And at some 70-80% throttle the secondary opens. But that other butterfly on top of the secondary doesn't. Its got a free moving lever outside the carburetor but I don't see anything that it is attached to it.
Is that normal? That it's always closed like that?

Sorry for this. I'm new at cars and hoping to know more so I can troubleshoot car problems myself.
So far, what I know about cars came from "Auto repair for dummies"


Tiny
Jicary
Jun 8, 2012.
Sorry. Above image is wrong.


Tiny
Jicary
Jun 8, 2012.
The top butterfly is the choke. If it is manual where you use a cable to engage, check the cable and adjustment. It should be open at all times, unless the choke cable is pulled.

If it is automatic, which is not likely to be unless the carb has been replaced with one of a later version, check if it is electrical or thermally opearted.
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KHLow2008
Jun 8, 2012.
So could it be the reason for limited speed and air burst?


Tiny
Jicary
Jun 8, 2012.
Yes, the engine would be running too rich with insufficient air getting into the engine and this would cause backfiring intermittently. The spark plugs would be sooty black under such conditions.


KHLow2008
Jun 8, 2012.
This helps me a lot.
There's nothing connected to it. So should I just try to clamp it open or something?
Uh. Wait. Is it still called a backfire when the air bursts come out from the air cleaner not the muffler?


Tiny
Jicary
Jun 9, 2012.
Exhaust is known as misfiring.

Coming out of the air cleaner is called backfire.

Can you show mw a picture of the carb choke? You can use something to hold it open but the idling speed at cold start would be low and it could possibly result in difficult starting and stalling, unless the idling speed is set high, maybe at 1000 rpm.


KHLow2008
Jun 9, 2012.
Ohhh. That's easier to understand : D thanks.

I used a nut temporarily to hold it open. Ill find something to hold it permanently. No problems in the starting and no stalling but there are backfires.

Uhm. Ill post a picture tomorrow. I left my car at my grandparents house. : D


Tiny
Jicary
Jun 10, 2012.

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