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Old 09-27-2011, 09:52 PM   #1
jklonowski
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Misfire and tail lamp issues

I have a Chevrolet with a 383 stroker with vortec head and hei. Only 5k miles.
When I hit the gas to take off it misses one time and sometimes when I get in the range of two to three thousand rpm it starts to misfire speracticly. I'm can't figure out what the problem is. I've rebuilt the carb, which is an edlebrock 600 and nothing changed. Also changed the plugs and wires and nothing changed. Changed the cap and button and still nothings changed. Pretty damn sure it's not a vacuum leak cause I only have four hoses one for the booster, the distributor, one for the Pcv, and one for the air controls. When I changed the plug wires I took out all of the plugs and looked at them and they looked good to me and so I put them back in. It ran really well for about a twenty min drive, then when I went to drive it the next day it started acting back up. So I went ahead and changed the plugs but it never got better. I gapped them to .045 and they were Bosch pp. I can't say for sure it's not the carb but I'm pretty sure. It's got a fairly new fuel pump and I just can't see the coil being the problem. I was told by many the coil works or it doesn't.

Also the left tail lamp and turn signal won't work all the time. Most of the time not. The reverse and running lights do. I've bought a new socket and didnt change a thing.

I know it's a long one but any ideas would be greatly appreciated cause I'm all out.

Thanks a lot
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Old 09-27-2011, 09:54 PM   #2
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Re: Misfire and tail lamp issues

check the connections at the rear harness and make sure the ground is good on the taillight.. i assume the bulb has been replaced more than once?
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Old 10-02-2011, 04:33 AM   #3
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Re: Misfire and tail lamp issues

Nothing?
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Old 10-02-2011, 02:44 PM   #4
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Re: Misfire and tail lamp issues

Double check the firing order for your engine and make sure your plug wires aren't loose at all. Trust me, I swore I had the correct firing order until I checked it with my mechanic handbook and it turns out I had 2 cylinders out of the firing order, rewired everything and she ran like a champ.
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Old 10-02-2011, 03:29 PM   #5
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Re: Misfire and tail lamp issues

If the firing order checks out check the distributor, had problems with an old Ford that would miss, backfire, and hesitate. Replaced the distributor, Pertronix kit for the points (always hated points) cap & rotor and ran like a champ. Always look at simple and cheap first.
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Old 10-02-2011, 03:30 PM   #6
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Re: Misfire and tail lamp issues

As for the tailight, check the ground. Almost 90% of the time for me this was the culprit.
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Old 10-02-2011, 09:30 PM   #7
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Re: Misfire and tail lamp issues

running a flat tappet cam in the 383?
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Old 10-03-2011, 03:16 AM   #8
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Re: Misfire and tail lamp issues

Alright guys thanks. I'll check it out tomorrow. I've noticed it's gotten a lot worse as far as the misfiring goes since it's gotten colder outside. Especially in te 2-3k rpm. I'd just hate to replacethe carb and it nit be the culprit cause that's a lot if money for me.
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Old 10-03-2011, 11:32 PM   #9
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Re: Misfire and tail lamp issues

You say the tail lamp is out but the running lights are on? Do you mean the brake lamp and turn signal are out? If so it could be your turn signal switch.

As for the miss fire it sounds like coil. Test the coil with an ohm meter for proper resistance. If it's not within range it's bad. You may also have the timing too far advanced. If the motor only has 5k or less miles the installer my not have grounded the motor properly which can effect the ignition system too
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Old 10-04-2011, 10:44 AM   #10
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Re: Misfire and tail lamp issues

check the vac advance springs move freely under the rotor
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