miss wont run help - Team Camaro Tech
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post #1 of 34 (permalink) Old Aug 18th, 14, 10:06 PM Thread Starter
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Ken
 
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miss wont run help

I'm new to this car and this working on cars in general. 383 stroker and it has been running great for the past 2 months. Fires right up and runs strong. I disconnected the battery and put new speakers in the front and back and a new head unit in that I ran of the BATTERY terminal on the block because the original battery power for the head unit was not there.

Start it up and it idled fine but had a bad miss. Feathered it and restarted it a couple times and got it worked out and it ran fine for a cruise. Next day same thing with same result. Took air cleaner off and saw power wire to electric choke was disconnected. Reconnected and no change. Today same issue but today wont even keep an idle and no noticeable fast idle. some burping and few backfire like sounds in with the carb

So does this sound like a fuel issue with the carburetor or spark and what is the first steps an armature newbie can try. Carb is a Demon either Street or Road...older one with no stamped model information. Any possibility the power feed for radio or disconnecting the battery messed up the MSD box or MSD coil?

help appreciated for a newbie
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post #2 of 34 (permalink) Old Aug 18th, 14, 11:03 PM
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Fred
 
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Re: miss wont run help

Give us a list of your combination.
Make, model, year, more about power train and accessories. And anything else that you changed or messed with during the speaker work.

One owner 69 Camaro,(yep, bought it new
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post #3 of 34 (permalink) Old Aug 19th, 14, 01:37 AM
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Scott
 
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Re: miss wont run help

In addition to replying with what Fred asked for, I would suggest you verify the electric choke is actually functioning properly. Next time before you start the engine (and before you put the key in the ignition or step on the throttle), remove the air cleaner and note the position of the choke butterfly. Now step on the throttle one time and the choke butterfly should move to a partially or completely closed position depending on temperature. Start the engine and let it run, within a few minutes the choke should begin opening and eventually open all the way in approximately five to seven minutes.

Let us know?

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post #4 of 34 (permalink) Old Aug 19th, 14, 05:12 AM Thread Starter
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Ken
 
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Re: miss wont run help

Thanks for the response.

Its a 1968 383 stroker with an edlebrock 383 stroker top end and a demon carb of unknown model. 4 speed. MSD wires, distributor, MSD box with 6000 chip and MSD coil. Everything else is stock other than spring stack and traction bars and rebuilt 3.73 rear end. Nothing else was messed with during the speaker work other than the neg battery cable disconnected and a power wire to the BAT tab on the block which I have since dis connected to rule that out.

I do think that the electric choke had the butterfly in the almost full open up/down position yesterday but I will check that out.
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post #5 of 34 (permalink) Old Aug 19th, 14, 07:26 AM
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Doug
 
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Re: miss wont run help

Can you post a picture of the routing of the wires for the MSD box. Also when powering the radio do you mean you ran the 12+ to the battery terminal in the fuse box? Make sure you have the 10 gauge red and 10 gauge black wire from the MSD box to the + and - battery terminals. Get a pair of spark plug wire puller and when you have the car running pull 1 spark plug at a time to see if you notice a change in that cylinder. Reinstall the wire and move on to the next one. If you find one that makes no change in the way the engine idles check ohms with a multimeter. Then look at spark plug and replace if necessary.
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post #6 of 34 (permalink) Old Aug 19th, 14, 04:26 PM Thread Starter
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Ken
 
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Re: miss wont run help

Ok so I removed and cleaned the fuel filter. It was fine. I took the air cleaner housing off and pushed the throttle with the engine off all the way and get nice squirts into the carb. It seems to be idling ok but has a miss at around 2000rpm and is sluggish on a tap of the throttle and burps/pops and backfire at the carb. No smoke or backfire at the exhaust. Attached are pictures of the set up under the hood. I plan to get a timing light in the next day or two and try to go down that path to at least make I have spark at all the cylinders.

So ruling out fuel delivery at this point does this still sound carb or now sprark/timing related....also keep in mind it was running great with no issues at all from the time I got it until parking it the other day and getting in it two days later. It worked through the problem and drove fine twice but now is not drivable at all So whatever happened just happened.





Last edited by AlotHP68; Aug 19th, 14 at 04:39 PM.
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post #7 of 34 (permalink) Old Aug 20th, 14, 09:14 AM
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rambojohnj
 
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Re: miss wont run help

I'd say spark plug(s) as well. Check them as Doug described. Good luck!
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post #8 of 34 (permalink) Old Aug 20th, 14, 09:15 AM
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rambojohnj
 
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Re: miss wont run help

Where are you at in Illinois?? If you are close, maybe we can meet up, and take a look at it. I am in Round lake
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post #9 of 34 (permalink) Old Aug 20th, 14, 11:26 AM
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Re: miss wont run help

If you haven't already, I would check for any loose wires around the battery. Especially that crimp connector on the positive side of the battery.
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post #10 of 34 (permalink) Old Aug 20th, 14, 04:01 PM Thread Starter
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Ken
 
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Re: miss wont run help

Ill check everything over again.

Could this all be from the electric choke not working? Cold the butterfly is not moving to a closed position. I am going to test the electric choke but I have a feeling its not working.
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post #11 of 34 (permalink) Old Aug 20th, 14, 05:45 PM
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Re: miss wont run help

Possibly, but I would tend to think not. I believe it's more of an electrical connection thing, since you were playing with the wiring. The choke was not hooked up before, but ran fine? I don't think it's cold enough for the choke to be needed, but I don't know what your engine needs.
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post #12 of 34 (permalink) Old Aug 20th, 14, 06:21 PM Thread Starter
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Ken
 
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Re: miss wont run help

I was also getting fast idle before and definitely am not now so I'm thinking the electric choke connector falling out is when things may have started.

I am getting around 12 ohms on the electric choke....from what I found that way to high. also the butterfly is stuck in one position and will not move. I cannot manually push it closed.

The only electrical I have touched was to disconnect the negative battery terminal and then run the power for the radio to an unused tab on the front of the fuse block that had power all the time.
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post #13 of 34 (permalink) Old Aug 24th, 14, 01:56 PM Thread Starter
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Ken
 
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Re: miss wont run help

Can anyone tell me what ohm reading they are getting on a working Demon/Holley style electric choke?
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post #14 of 34 (permalink) Old Aug 24th, 14, 02:46 PM
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Steps
 
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Re: miss wont run help

Quote:
a miss at around 2000rpm and is sluggish on a tap of the throttle and burps/pops and backfire at the carb.
u may not have moved any HT leads...To get a back fire thru a carb u NEED an ignition while a firing cylinder is open...
This can only be caused by a couple spark plug wires wrong
or a valve mis adjusted and open...
or cross fire between HT leads
or broken, cracked dirty Dizzy cap rotor.

Check #1 is set to fire on compression stroke (thumb on #1 spark plug hole to feel for the compression stroke)
Check and re check HT lead order.
Inspect rotor/ cap inside and out with a magnifying glass looking forand arc trails / cracks... then clean
Run motor on a dark night and feel/ watch for any arching...

Remove the MSD unit, and with it in hand, walk out of the garage, place your hand as far behind u as possible, then bring your hand in a very fast arch, releasing the msd unit at the right to to accurate it in a manner for greatest distance and height.
Return to the garage and car.
The reasons why, I have expressed several times in old posts.

My Spelling is not incorrect...it is creative

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post #15 of 34 (permalink) Old Aug 24th, 14, 05:18 PM
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Don
 
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Re: miss wont run help

Only thing I ask is could your msd box be shorting out internally?
Second, I don't see where you have the msd box grounded.

Last, Steps, You know something I would like to know about R&R the msd and walking outside the garage with. Can you share? I am thinking something in the lines of polarity?
Usually when I walk out of the garage and back its because something that hacked me off and I need to cool off. Know what I mean? Might pick up any tools I threw out in the drive way too.

Don
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