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Backfire 3000 Rpms Help !

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#1 zuluaga63

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Posted 12 March 2013 - 05:39 PM

hello i need help with my austin mini 1988
engine 1000 i bought it 2 months ago i need help because when i'm driving and the rpms reaches 3000 it starts to backfire and the rev gauge goes crazy ... can someone help me out !
what can be the problem

i checkt the distributor but it looks fine (clean it )

here is a video of the problem the sound its not good beause cell phone hits the steering wheel



#2 smartie93

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Posted 12 March 2013 - 05:43 PM

I can't hear a backfire in the video, but that just might be the video. Is it backfiring through the carb or the exhaust?

#3 zuluaga63

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Posted 12 March 2013 - 05:45 PM

im not sure, but i think the exhaust. i will go out again later and check that really quick

#4 Harrison541

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Posted 12 March 2013 - 06:53 PM

Could be mixture too rich, valve timing out or distributor not aligned properly. Its worth checkning those first

#5 Stevie W

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Posted 12 March 2013 - 07:03 PM

Hi,

Judging by the fact your rev counter appears to lose its "signal" at about 3000rpm (needle dropping sharply) I would say it's an ignition problem.
If your distributor has points/condensor I would check the points gap and try another condensor. If its got electronic ignition it might be the amplifier module breaking down at higher revs.

I had a similar problem a few years back, and that was the coil winidings breaking down. I'd tighten the coil clamp too much and it punctured the bodyof the coil and caused a short from the winidings to the clamp. This showed up as a mis-fire around 4000rpm!

Hope this helps!

Steve.

Edited by Stevie W, 14 March 2013 - 06:01 PM.


#6 zuluaga63

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Posted 12 March 2013 - 07:37 PM

tomorrow am going to check all of that thanks for the help !

#7 jaydee

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Posted 12 March 2013 - 08:01 PM

Its an ignition problem at low tension circuit, possibily the coil

#8 zuluaga63

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Posted 12 March 2013 - 10:01 PM

so what should i do first change the coil ? or what could i need to do first?

#9 jaydee

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Posted 12 March 2013 - 10:05 PM

First check points and condenser (corrosion, wear, signs of burning) points clearance (15 thou) and -ve lead of the coil for corrosion. If no avail try a different coil.
You can check the coil resistance with a multimeter but so many times it has proved nothing..

Edited by jaydee, 12 March 2013 - 10:06 PM.


#10 Gulfclubby

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Posted 13 March 2013 - 03:15 PM

Sounds a lot like bad points gap. Mine did that at some point. Cleaning and adjusting the points solved it.

#11 dklawson

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Posted 13 March 2013 - 04:22 PM

As above, the tach behavior says the problem is electrical and part of the ignition system low-tension circuit.

Do not start with the coil. Take Jaydee's (and others') advice and go through the points and condenser first. Always start with the cheap stuff. Save the coil for last.

While you are working on the items inside the distributor, take a close look at any flexible wires going between the breaker plate and the distributor housing. Some use an earth wire between the plate and the dizzy housing. If this fails you can get weird ignition problems. If you have points there will also be a wire from them to the "outside". If that wire breaks the ignition system will stop working. In both cases, the problem may not show up until the advance mechanism starts to kick in.

#12 Gulfclubby

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Posted 13 March 2013 - 09:24 PM

Also make sure the points surface is clean. Insufficient points gap can cause an arc building between the two parts of the contact breaker, which can cause microweld residue to form on the surface, which does not conduct or poorly. If there is any dark residue, file/sand it off carefully or replace the points with new ones.

#13 zuluaga63

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Posted 14 March 2013 - 08:15 AM

if i replace the point with new ones how do i calibrate them ? does anyone have a video or some guide i can used

thanks for the help ! everyone

#14 Gulfclubby

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Posted 14 March 2013 - 09:25 AM

same basic principle for all points distributors.

#15 zuluaga63

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Posted 14 March 2013 - 10:51 AM

i opened my distributer again to clean the points, i cleaned them but still keeps doing the same stuff, the points look really old im going to order new points also the condenser, if that doesnt work then i would change the coil.

thank for the video !

super mini mad.







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