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Stalling and limited speed

Tiny
JICARY
  • MEMBER
  • 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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Monday, June 4th, 2012 AT 12:39 PM

27 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Don't quite understand your problem-check the choke plate adjustment/carb linkages
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Monday, June 4th, 2012 AT 1:28 PM
Tiny
KHLOW2008
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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.
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Monday, June 4th, 2012 AT 4:08 PM
Tiny
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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"
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Friday, June 8th, 2012 AT 5:56 AM
Tiny
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Sorry. Above image is wrong.
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Friday, June 8th, 2012 AT 5:59 AM
Tiny
KHLOW2008
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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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Friday, June 8th, 2012 AT 12:42 PM
Tiny
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So could it be the reason for limited speed and air burst?
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Friday, June 8th, 2012 AT 1:58 PM
Tiny
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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.
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Friday, June 8th, 2012 AT 2:26 PM
Tiny
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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?
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Saturday, June 9th, 2012 AT 2:00 AM
Tiny
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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.
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Saturday, June 9th, 2012 AT 2:39 PM
Tiny
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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
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Sunday, June 10th, 2012 AT 2:04 PM
Tiny
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For backfiring, it could be due to the rich condition, ignition timing too advanced, a poor cylinder, spark plug and/or related components. That would require tests to confirm.
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Sunday, June 10th, 2012 AT 2:29 PM
Tiny
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Spark plugs are new.
What does ignition timing mean?
After letting the choke butterfly open. The backfiring reduced. But is still there.
Here are the pictures
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Tuesday, June 12th, 2012 AT 4:15 AM
Tiny
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Ooopppsss
pictures.
Here.
Sorry there's nothing much to see.
It was night time when I took these
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Tuesday, June 12th, 2012 AT 4:22 AM
Tiny
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Ignition timing means the time the spark plugs fires. It is adjusted by turning the distributor clockwise or counterclockwise and you use a timing light to check. If contact breaker points are used, the gap clearance would affect the timing. The wider the gap, the more advanced it is.

I don't see any choke plate in the pictures.

The rubber capped plunger at bottom of last picture is the accelerating pmp. Ensure you have a fine spray into the carb at top inner part of carb barrel. If there are none or is too little, you would have hesitation and possibly backfiring as well.
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Tuesday, June 12th, 2012 AT 6:17 PM
Tiny
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When I press the pump it sprays fine. But the secondary doesn't spray any.
Sorry its the picture, you cant see the plate because it's too dark. Notice the second barrel is dark while the first one, you can see the butterfly(gold). The secondary is closed.
Should both of them spray gas at the same time? Or is it supposed to spray on the secondary only when the second barrel opens?
Ill take new pictures. Those you can see :D
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Thursday, June 14th, 2012 AT 1:53 AM
Tiny
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The secondary does not have any accelerating pump functions. Only the primary has it.

I can't seem to be able to see the pictures now as they are not loading correctly. Maybe I will try again later.
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Thursday, June 14th, 2012 AT 1:37 PM
Tiny
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Ohh... i thought it's supposed to be pumping as well :D
haha. sorry about that. new knowledge for me.
i forgot to take pictures earlier this day. haven't been able to go to my grandparents house. that's where the car is.
thanks for taking the time to help me with this problem.

here's the picture..
http://cdn.2carpros.com/question_images/34361/large.JPG?1339474936

why does it have an exit when there's no pump action for that barrel?
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Thursday, June 14th, 2012 AT 2:13 PM
Tiny
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The accelerating spray is from the side of the barrel. The central venturi for the primary and secondary are for fuel to flow when suction is created by air flowing through it. They do not spray.

I was expecting a big butterfly covering the barrel. Seems it is only for the primary venturi.
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Thursday, June 14th, 2012 AT 5:40 PM
Tiny
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I took a video of my carburetor.
I'm gonna upload it later.
I let the choke stay open. I tested and it still backfires every once in a while. The secondary butterfly opens well at 70-80% throttle but I'm still having the backfiring problem.
Also, the engine power is very low. I'm having a hard time with this.
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Friday, June 15th, 2012 AT 2:05 PM
Tiny
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http://youtu.be/qgCHUGjFWtE
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Friday, June 15th, 2012 AT 5:07 PM

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