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notes1952
Joined: Mon Jan 04, 2010 10:30 pm Posts: 5 Location: Valley Heights, NSW
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 Posted: Wed Jan 06, 2010 1:50 pm |
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Hi all - I have a 1988 G16A Vitara with a very bad miss on acceleration. I believe I have narrowed it down to a failure of the secondary butterfly to open. The motor idles perfectly but as revs increase it then seems to starve for fuel until I manually open the secondary with a screwdriver at which point it accelerates perfectly.
Any suggestions on what could be causing this & how do I fix it?
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11_evl
Joined: Tue Apr 10, 2007 11:30 pm Posts: 846 Location: logan reserve, Brisb
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 Posted: Wed Jan 06, 2010 2:19 pm |
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you sure the plugs, leads, or coil arnt breaking down.
_________________ 92 sierra, 40" treps, full hydro, F&R steer, 106"W
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notes1952
Joined: Mon Jan 04, 2010 10:30 pm Posts: 5 Location: Valley Heights, NSW
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 Posted: Wed Jan 06, 2010 5:49 pm |
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11_evl wrote: you sure the plugs, leads, or coil arnt breaking down.
I have already replaced the plugs, the coil is fairly new but I have yet to replace the leads. I have also found that if I spray some fuel down through the secondary throat it accelerates without a problem tending to suggest an issue with the fuel supply through the secondary.
Dave.
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want33s

az supporter
Joined: Fri Nov 16, 2007 10:30 pm Posts: 8134 Location: Sunshine Coast Qld
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 Posted: Wed Jan 06, 2010 6:32 pm |
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Sounds like a blocked vaccuum passage. Air blower is your friend.
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MacDaddy

az supporter
Joined: Thu Mar 26, 2009 10:30 pm Posts: 10453 Location: Perth, Australia
Vehicle: Jeep
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 Posted: Wed Jan 06, 2010 8:35 pm |
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I would be checking some of the small rubber hoses that connect all over the carby as well, as i have found some that where very loose, and one just slid of in my fingers...
Also, i would be changing the fuel filter by the tank, if its original, it wouldnt be working to well anymore, any crap that gets through wont help the carby... 
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notes1952
Joined: Mon Jan 04, 2010 10:30 pm Posts: 5 Location: Valley Heights, NSW
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 Posted: Tue Feb 16, 2010 11:49 am |
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Hi all,
got the carby overhauled & runs well now. Apparently the diaphragm that controls the secondaries had also failed. Also found as suggested that a number of the vacuum lines were suspect so replaced these.
Only problem now is that it idles fine at around 500rpm but if the lights are turned on the idle hunts between 500 & 1500 rpm. I am going to check the obvious connections such as battery etc. Any other suggestions?
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JrZook
Joined: Tue Aug 08, 2006 11:30 pm Posts: 5517 Location: Holland Park
Vehicle: Awesome!!
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 Posted: Tue Feb 16, 2010 3:28 pm |
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notes1952 wrote: Hi all,
got the carby overhauled & runs well now. Apparently the diaphragm that controls the secondaries had also failed. Also found as suggested that a number of the vacuum lines were suspect so replaced these.
Only problem now is that it idles fine at around 500rpm but if the lights are turned on the idle hunts between 500 & 1500 rpm. I am going to check the obvious connections such as battery etc. Any other suggestions?
There's an idle up solenoid that get activated once electrical load is present (lights, blower fan etc). Get someone to turn the lights on and off while the engine is idling. Study the carb you will find the idle up actuator and thus be able to adjust it to give a descent idle speed.
Dan
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MacDaddy

az supporter
Joined: Thu Mar 26, 2009 10:30 pm Posts: 10453 Location: Perth, Australia
Vehicle: Jeep
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 Posted: Tue Feb 16, 2010 9:33 pm |
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notes1952 wrote: Hi all,
got the carby overhauled & runs well now. Apparently the diaphragm that controls the secondaries had also failed. Also found as suggested that a number of the vacuum lines were suspect so replaced these.
Only problem now is that it idles fine at around 500rpm but if the lights are turned on the idle hunts between 500 & 1500 rpm. I am going to check the obvious connections such as battery etc. Any other suggestions?
Cool !
Mine does similar, but holds at 1500rpm , not sure if it is normal or not... i am guessing it works off the Auto choke somehow... tends to do it more in colder weather... but i do know the carby needs to be tuned when hot and cold, so yeah, maybe thats all it needs... 
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