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'86 brat poor starting / idle?


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9 replies to this topic

#1 belacane

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Posted 09 October 2012 - 11:29 PM

So I recently brought a 'new' '86 Brat from Utah home to Chicago.

An interesting thing happened on my drive back. On my second morning on the road in Nebraska, I started her, and she'd start, go to about 1200 rpms and then slowly drop rpms and die.
This has continued through Iowa and in Chicago. It didn't happen in Utah at all as far as I experienced.
It's usually only happens on the first start of the day or if she's been sitting for more than 6 or 7 hours.

I temporarily solve the problem by giving her some gas while in neutral and within a minute or so the rpms will hold stable at 1000, but as I drive, the idle feels rougher than it used to.

This is my first foray into carburated engines, so I'm unfamiliar with what is normal. I'm also curious if it has anything to do with the change in altitude (Chicago is nearly sea level while Utah is at something around five thousand feet), and the air mixture in the carb.

Thanks in advance for your kind input!

#2 ShawnW

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Posted 10 October 2012 - 12:01 AM

When you cold start it are you depressing the gas once before cranking?

#3 letank

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Posted 10 October 2012 - 02:04 AM

IIRC, the carb has an altitude compensation adjuster, that is not automatic, it is done by turning a screw.... Forgot the location.... But lean idle would make it hard to start, and hard to drive, likely to stall as you accelerate from a stop.

Time to check the basics, spark plugs, vacuum leaks....loose connectors...

#4 Hitoshi

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Posted 10 October 2012 - 03:46 AM

Ditto on what Shawn said. At least on my Weber hitting the accelerator is needed to "reset"/close the choke. Not sure if this is your issue but I had similar problems and it was all due to the choke not functioning correctly.

#5 belacane

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Posted 10 October 2012 - 08:35 AM

When you cold start it are you depressing the gas once before cranking?



I haven't tried that yet. I will try it today and post results!

#6 belacane

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Posted 10 October 2012 - 12:09 PM

I haven't tried that yet. I will try it today and post results!



Tried depressing the throttle today before starting and it didn't seem to have any effect.

Gonna check hoses and plugs...etc. but the thing that puzzles me is that it's only for the first start of the day. If i go for a drive and then start her up again, all is well.

#7 letank

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Posted 10 October 2012 - 02:40 PM

Tried depressing the throttle today before starting and it didn't seem to have any effect.

Gonna check hoses and plugs...etc. but the thing that puzzles me is that it's only for the first start of the day. If i go for a drive and then start her up again, all is well.


the first time of the day....

As said... recheck your choke operation.... flapper too close or too open.

Next:
1) Some dew on electrical, take the distributor cap off, and clean it up.... my civic is terrible for that... one morning no start.... clean the crap inside the cap.... started well, my fuel level is fine.... but first stat is not good.
2) May be the fuel is low in the bowl, fuel drains overnite.

#8 phantomD

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Posted 12 October 2012 - 06:24 AM

I have this exact same problem which is not any of the items already mentioned (it would seem). I look forward to hopefully being able to solve it with this thread.

#9 ferox

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Posted 12 October 2012 - 02:31 PM

This is my first foray into carburated engines, so I'm unfamiliar with what is normal. I'm also curious if it has anything to do with the change in altitude (Chicago is nearly sea level while Utah is at something around five thousand feet), and the air mixture in the carb.


I would suspect so. You should check all your jet sizes and locations and float setting to see what you've got. The idle jets are on the outside of the carb and the air correctors and mains are on the inside. You just have to remove six screws and disconnect the choke linkage to get to the inside where the float and jets are. It's pretty easy actually.

#10 belacane

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Posted 14 October 2012 - 03:58 AM

Thanks everyone for the input....this is all on my list of stuff to do! I will post updates on how it goes!




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