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Old 11-24-2018, 09:44 AM   #1
85/Silverado
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Back Fire

I had trouble with my Distributor staying still so I bought a new hold down and that seams to keep it still.
I notice that anywhere we set the timing it back-fires and stalls at low idle. I'm suppose to retard the timing a little to keep it from spark knocking but it doesn't seam to matter where we set it now.
I'm replacing the Carb. Tuesday since the one I have on it now has a broke choke and I've had trouble with it since I bought it.
I don't think anyone has touched the plug wires since they are run to be unseen. I'll have him check for a short and make sure they are all working.
The truck has sat since the Hurricane Oct. 10 and maybe the gas went bad.?
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Old 11-24-2018, 12:24 PM   #2
68gmsee
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Re: Back Fire

Backfires through the exhaust or carb?

Since it's only been a little over a month since it was parked and if truck was run frequently prior to the hurricane, I doubt the gas is the problem. There's several things that can cause backfiring so start with the basics.

First, use a timing light and set the timing to specs then start trouble shooting from there. Check for vacuum leaks, bad ignition parts like wiring and spark plugs. If you have HEI check distributor cap and rotor and make sure the ground strap under the coil is not rusted. Moisture can do that if it's been very wet where the truck sat and it's easy to check it.
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Old 11-24-2018, 02:00 PM   #3
85/Silverado
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Re: Back Fire

Yes HEI Thanks for some Ideas.
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Old 11-24-2018, 04:15 PM   #4
Dead Parrot
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Re: Back Fire

Might double check that the wires are installed on the dizzy in the correct order. Not at all unusual for a pair to get swapped during dizzy work.

Might pull the cap and make sure some small multi-legged critter didn't seek shelter and has since been pureed into conductive goo.

2nd the thought that the gas should not go bad in only a couple of months. Now if the truck was outside during the storm, possible water got blown into the tank. Tornado winds can do weird crap, figure hurricane winds can as well.

Wait until dark, start it and look for sparks. Quick way to spot bad wires.
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Old 11-24-2018, 08:33 PM   #5
68gmsee
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Re: Back Fire

Quote:
Originally Posted by Dead Parrot View Post
...
Wait until dark, start it and look for sparks. Quick way to spot bad wires.
Good point ^. I had a car with bad wires once and did just that. I used a water spray bottle to mist them and they arced like Teslas' coil.
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Old 11-24-2018, 09:02 PM   #6
85/Silverado
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Re: Back Fire

I'm surprised my Truck and Car survived Michael in the first place. Not a tree in my yard or the neighbors did.
Thanks for more ideas.
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