Ignition OR Carb problem ??
Thread Starter
Drifting
Joined: May 2005
Posts: 1,909
Likes: 6
From: Lake Arrowhead - Georgia > 72 Base Coupe & 74 BB Roadster
Ignition OR Carb problem ??
Feels like Carb, but I have been tricked by Ignition before! 
Suddenly on the last drive into town.... the 74 / 454 (GM HEI - no points) would sputter and spit when coming to a stop AND if at idle when coasting downhill. Each time it went dead I held WOT until it would clear and start. It was sporatic and it always started back up after the carb cleared.
I havent had time to mess with it ..... but WHY would the "battery" gauge be pegged full 40+ EVERYTIME this occurred. Each time it would smooth back out, the "battery" gauge went back to normal.....spitting and coughing - pegged full right! Could this be an alternator dying (?) rather than a carb problem ? I may "test / replace" the alternator before screwing around with a Lars Carb that I have full faith in.
Suggestions appreciated........
Suddenly on the last drive into town.... the 74 / 454 (GM HEI - no points) would sputter and spit when coming to a stop AND if at idle when coasting downhill. Each time it went dead I held WOT until it would clear and start. It was sporatic and it always started back up after the carb cleared.
I havent had time to mess with it ..... but WHY would the "battery" gauge be pegged full 40+ EVERYTIME this occurred. Each time it would smooth back out, the "battery" gauge went back to normal.....spitting and coughing - pegged full right! Could this be an alternator dying (?) rather than a carb problem ? I may "test / replace" the alternator before screwing around with a Lars Carb that I have full faith in.
Suggestions appreciated........
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
One of my favorite Larsisms is that 90% of carb problems are actually ignition problems. Good idea to always check the ignition system, which can be effected by electrical issues, first.
TSW
TSW
Thread Starter
Drifting
Joined: May 2005
Posts: 1,909
Likes: 6
From: Lake Arrowhead - Georgia > 72 Base Coupe & 74 BB Roadster
You guys are confirming what I thought......check everything else first (especially electrical / timing) when it appears to be a carb problem. I'll follow up with what it turns out to be. I am leaning to alternator - volt regulator, because this car was "tuned dead on" and the entire underhood is all new .... except the alternator. It very well could be the original part.
Last edited by fotyfobravo; Feb 25, 2009 at 12:00 PM.
Race Director
Joined: Mar 2006
Posts: 14,112
Likes: 28
From: Florida
Feels like Carb, but I have been tricked by Ignition before!
Suddenly on the last drive into town.... the 74 / 454 (GM HEI - no points) would sputter and spit when coming to a stop AND if at idle when coasting downhill. Each time it went dead I held WOT until it would clear and start. It was sporatic and it always started back up after the carb cleared.
I havent had time to mess with it ..... but WHY would the "battery" gauge be pegged full 40+ EVERYTIME this occurred. Each time it would smooth back out, the "battery" gauge went back to normal.....spitting and coughing - pegged full right! Could this be an alternator dying (?) rather than a carb problem ? I may "test / replace" the alternator before screwing around with a Lars Carb that I have full faith in.
Suggestions appreciated........
Suddenly on the last drive into town.... the 74 / 454 (GM HEI - no points) would sputter and spit when coming to a stop AND if at idle when coasting downhill. Each time it went dead I held WOT until it would clear and start. It was sporatic and it always started back up after the carb cleared.
I havent had time to mess with it ..... but WHY would the "battery" gauge be pegged full 40+ EVERYTIME this occurred. Each time it would smooth back out, the "battery" gauge went back to normal.....spitting and coughing - pegged full right! Could this be an alternator dying (?) rather than a carb problem ? I may "test / replace" the alternator before screwing around with a Lars Carb that I have full faith in.
Suggestions appreciated........
Don't know how long you crank on it, but if the battery isn't up to snuff, it will show a full charge for a bit after a lot of cranking.
On the distributer side check this and solder the wires. This creates a lot of intermittant problems such as unexpectantly cutting out for no reason.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
This is going to sound out in 'left field', but the curious thing is the ammeter going to full scale (+) reading. I'm wondering if the fuse-link or part of the wiring in the ammeter line is going bad causing its resistance to increase. That would cause the ammeter to read high AND for the actual voltage in that line to drop...which might cause problems with the ignition system. Again, I'm trying to come up with a fault that matches with your 'symptoms'.
Thread Starter
Drifting
Joined: May 2005
Posts: 1,909
Likes: 6
From: Lake Arrowhead - Georgia > 72 Base Coupe & 74 BB Roadster
This is going to sound out in 'left field', but the curious thing is the ammeter going to full scale (+) reading. I'm wondering if the fuse-link or part of the wiring in the ammeter line is going bad causing its resistance to increase. That would cause the ammeter to read high AND for the actual voltage in that line to drop...which might cause problems with the ignition system. Again, I'm trying to come up with a fault that matches with your 'symptoms'.
What is throwing me off is that just at a cruise....it will suddenly act like it is FLOODING, ..... but at the same instant, the amp meter goes from normal to full 40+. As soon as it "clears" - the amp meter is back normal. Battery is only a month old. Thanks again....Fred
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Le Mans Master
Joined: Jan 2000
Posts: 8,918
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From: New Hill NC
Often I find that "left field" works well when test shooting a problem.
What is throwing me off is that just at a cruise....it will suddenly act like it is FLOODING, ..... but at the same instant, the amp meter goes from normal to full 40+. As soon as it "clears" - the amp meter is back normal. Battery is only a month old. Thanks again....Fred
What is throwing me off is that just at a cruise....it will suddenly act like it is FLOODING, ..... but at the same instant, the amp meter goes from normal to full 40+. As soon as it "clears" - the amp meter is back normal. Battery is only a month old. Thanks again....Fred
Melting Slicks
Joined: Jul 2004
Posts: 2,577
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From: Long Island New York
