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daniel911T daniel911T is offline
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Join Date: Apr 2010
Location: Jacksonville, FL
Posts: 806
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Question Weak spark troubleshooting

Hey everyone!

I have an MSD 6AL and a Blaster SS coil in a 1969 Porsche 911. I am using a pertronix in the stock Bosch distributor for triggering. Coil wire is about 2' long 8mm MSD. Plug wires are 8.5mm Magnacor competiton wires (from our host). 6AL and Blaster SS coil are about 7 years old, but have driven less than 10K miles.

I have just installed a new set of Zenith carburettors and the car has been sitting for about 5 months. It was running when stored.

I have a no/weak spark problem now:
1. When the coil wire is placed close to ground (1/4" or closer) and the white wire is grounded I do get a spark. No spark at the 1/2" directed in 6AL instructions.

2. When I place the coil wire near ground and crank the engine, I do get multiple sparks. (Pertronix works)

3. When I attach a spark plug to the end of the coil wire at the installed gap (.060" Bosch WR5DC+) and ground the threaded part of the plug, then ground the white wire, there is no spark, but I can hear the MSD making the normal noises (high pitched noise)

4. When I attach a plug with a much smaller gap (.025 NGK BP6ES) and do the same proceedure, I also get no spark.

Battery is fully charged and reads 13V, engine cranks quickly.

What could cause this weak spark condition?

Thanks!
-Dan
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1969 911T (Getting a 72E heart transplant)
2004 Volvo XC70
Gone, but not forgotten:1971 Bug, 1978 Bus, 1982 Westy, 1996 GTi, 2000 Audi A4 2.8, 2001 Jetta Wolfsburg 1.8T, 2002 Audi allroad 2.7T, 2010 Jetta SportWagen TDi, and a couple of short lived 914s.

Last edited by daniel911T; 08-17-2011 at 10:13 AM..
Old 08-17-2011, 10:10 AM
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