Backfiring issue

Electrical and Ignition

  1. A56

    A56 MoPar Affliction

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    :popcorn:
     
  2. davidcribbs

    davidcribbs Well-Known Member

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    I had been doing diagnostics, and even relenting and taking it to the shops. When I realized after I got it back from one of the shops, and they told me the carb was bad. Took apart the whole ignition system and realized the distributor cap was in bad shape. Not sure where the thought that I was just throwing money away? The compression is not bad, I checked it finally.
     
  3. A56

    A56 MoPar Affliction

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    I don't believe he directed that at you, but ya neva know,
     
  4. pishta

    pishta I know I'm right....

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    backfire is ignition timing, spark on the intake somewhere. pull #5 and try and start it, then try with 7 disconnected only. this may help diagnose an arcing plug wire. Id also check your advance plate for proper movement when applying vaccum to the pot. must snap back.
     
  5. davidcribbs

    davidcribbs Well-Known Member

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    Yep, in agreement on the timing issue. Didn't think about the arcing wires, but good place to start with those. Thanks.
     
  6. pishta

    pishta I know I'm right....

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    can arc in old carbon traced cap too.
     
  7. Dartswinger70

    Dartswinger70 Only thing I ever bought new was a Fender Strat

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    Alot of "Diagnostics" comes from experience, but every now and then you'll be in a hurry and throw parts. LOL! I was in the auto business and even went to trade school for it. I remember this basic principle, "there are four things that will make an engine not run, no fuel, no spark, timing, and mechanical failure" such as a jumped timing chain, or head gasket blown etc. I would check fuel with a can of carb cleaner, on carb or FI engines spray a blast or tree down the throat ,crank it if it fires and runs 10 seconds you have spark...that test takes 10 minutes max. That will also tell you if the timing is good if it runs smooth for those 10 seconds. Then you know its fuel delivery and you focus on that. if the car starts and backfires and runs like crap, its timing or mechanical failure. than you go from there. It doesn't take al day to do diagnostics, and you basically "follow your nose" like a detective. You don't get into tearing everything apart, you focus on an "area" to take things apart, if you think its valvetrain ,you pull the rocker covers and look etc.
     
  8. RustyRatRod

    RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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    Up until the FIRST SENTENCE in the above post, you said nothing about anything except parts replacement, so how was anyone supposed to know you diagnosed anything? A crystal ball? As for the throwing money away comment, it was a general statement about what the lack of diagnosis will get you. Have you made any progress? I have a couple of things you might try if not.
     
  9. RustyRatRod

    RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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    Yes and sometimes part of diagnosis IS trying another part.
     
  10. davidcribbs

    davidcribbs Well-Known Member

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    Yep, you are correct, I could have elaborated more. At the same point, I didn't really want to make my post 4 pages long.

    The burnt contact points on the distributor cap were due to a replacement ignition module that a mechanic in my area installed, when the previous one smoked while they were tracing a draw in the engine. I rewired the whole car from the bulkheads forward, and from the intermediary to the rear. Little did I know that when I purchased the rear wiring harness from Year One, that the tail light wires were reversed. I as well had a lot of additional issues with the wiring that one of the many owners prior to me tried to Jerry-rig that was causing several different contact points that were drawing down my battery in the under-dash harness.

    Interesting enough, the mechanic that I took it to (recommended heavily in my area for good work on older cars) identified the spark plugs wires being bad (and subsequently replacing them), but failed to check the distributor cap. Obviously re-enforces my reservations towards taking any of my cars to someone else to look at them. Unfortunately with the Covid crap going on, my work has been taking more time away from me working on my own cars. I reluctantly took it to a mechanic, and got what I deserved I guess.

    I have finally made some progress. I have been able to get it started, but three things were affecting the car. The first (and all on me), when I replaced the plugs a couple of weeks ago I flipped #6 and #8 wires. I also was not getting enough juice from the battery to create a good spark, and due to the battery dragging I had the timing retarded to make it kick over. Once I switched the plug wires, and threw in the new battery it started up. I haven't had a chance to set the initial timing or run the vacuum gauge on the carb, but I am hopeful tonight I will get the chance.

    I appreciate everyone's input, and if not for that, I am sure I would still be chasing ghosts in the car. Thank you all.
     
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    • RustyRatRod

      RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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      Man, I've been doin this stuff since 1974, when I was NINE YEARS OLD and to this DAY, I still booger up plug wire firing order on occasion. It happens. lol
       
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