No spark from coil - low voltage across leads
06-08-2011 | 10:47 PM
#1
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No spark from coil - low voltage across leads
I'm starting to wonder if I'm ever going to hear this damn engine run! First the exhaust alignment issue, broken head bolt, then the coupler issue, and now this! 
I went to fire it tonight, but alas, no spark. Checked connections at the coil, verified that rotor and distributor cap looked OK (both are new), but still no dice. I ran a DVM across the leads on the coil, and it was only showing around 7 volts. Checked voltage at pin #5 on the main connector (purple wire), and was getting 12.7 V there. Disconnected leads on the coil, and if I put positive lead on the purple wire coming in from the harness, and then run the3 negative lead on the DVM back to the battery ground I get 12+ V. However, if I touch the wires attached to the ground side of the coil, voltage drops back to 7 V. It seemed that the voltage only was dropping when the coil was hooked up to the wires. It did the same thing when I ran a wire directly from the positive side of the coil to the pos side of the battery, and still no spark.
So I borrowed another coil - no change. Installed a different ignition module - no change. Checked and double checked all my ground connections on the back of the engine, but did not find anything loose.
The only component I have not replaced is the pickup coil in the distributor. Could this cause symptoms like this? Other than this, I guess I will have to go through the engine wiring harness piece by piece.
Looks like another lake trip without my boat! Damn I hate electrical problems!
I went to fire it tonight, but alas, no spark. Checked connections at the coil, verified that rotor and distributor cap looked OK (both are new), but still no dice. I ran a DVM across the leads on the coil, and it was only showing around 7 volts. Checked voltage at pin #5 on the main connector (purple wire), and was getting 12.7 V there. Disconnected leads on the coil, and if I put positive lead on the purple wire coming in from the harness, and then run the3 negative lead on the DVM back to the battery ground I get 12+ V. However, if I touch the wires attached to the ground side of the coil, voltage drops back to 7 V. It seemed that the voltage only was dropping when the coil was hooked up to the wires. It did the same thing when I ran a wire directly from the positive side of the coil to the pos side of the battery, and still no spark.
So I borrowed another coil - no change. Installed a different ignition module - no change. Checked and double checked all my ground connections on the back of the engine, but did not find anything loose.
The only component I have not replaced is the pickup coil in the distributor. Could this cause symptoms like this? Other than this, I guess I will have to go through the engine wiring harness piece by piece.
Looks like another lake trip without my boat!
Damn I hate electrical problems!
06-09-2011 | 06:24 AM
#3
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Joined: Jun 2004
Posts: 1,949
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From: Omaha, Nebraska. Boat on the Mighty Mo! Longest river in the USA!
Weak spark -
The sensor has nothing to do with it, just like the advance control module. They work or they don’t. Weak spark, first think check the battery. I worked on a boat last year with similar problems. Owner said it turned over fine but would not start. I put a volt meter on it and turned the engine over. It dropped in volts so low the spark was to weak to start the engine. Silly as this sounds I charged the battery for three hours and it started right up. Owner could not believe it, and what I charged him to charge a battery.
The sensor has nothing to do with it, just like the advance control module. They work or they don’t. Weak spark, first think check the battery. I worked on a boat last year with similar problems. Owner said it turned over fine but would not start. I put a volt meter on it and turned the engine over. It dropped in volts so low the spark was to weak to start the engine. Silly as this sounds I charged the battery for three hours and it started right up. Owner could not believe it, and what I charged him to charge a battery.
06-09-2011 | 09:15 AM
#4
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Joined: Mar 2011
Posts: 119
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From: St. Louis, MO
As I read on, I thought the same thing about the battery...sounds insulting but give it a shot if you haven't.
