93 VW Golf won't start when wet

I have a 1993 vw golf 2.0 5speed 150k. I bought it used and have replaced the distributer (dealership). Coil, cap, rotor. There is gas but no spark, let the car dry out it starts right up. There are three wires going to the coil. One is a heavy black wire that is hot when the ignition switch is turned on. When the car is wet this black wire is dead going to the coil when the key is switehed on. THe car cranks over normally, no bangs, pops or runs.

1. Yes somewhere it is grounding out but I cannot find any arcing. Would any of the sensors stop the electric flow to the coil? Could the fuse box itself be drawing damp thus stopping the flow?

2. It has crossed my mind to jump the heavy black wire direct from the hot side of the battery to start the car when this wire is dead. Would this damage the car?

Mike, ps After going thru the glove box found many receits stating car will not start when wet!
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have the same problem?
Tuesday, August 7th, 2007 AT 3:30 PM

1 Reply

This is one of those fun problems that you get to troubleshoot most effectively when the problem is occurring. Wait for a wet day when the car is not starting. Disconnect the negative battery cable before you start. Get yourself a continuity tester (usually under $5 at a hardware store) and get to work. Start first by visually inspecting the entire length of the wire for breaks in the insulation.

The continuity tester has a battery for power, a pointed tip, and a single wire coming off that ends in a small alligator clip. Attach the alligator clip to the coil end of the dead wire, and begin checking the length for continuity. You'll need to pierce the insulation of the wire with the pointed end of the continuity tester to reach the wire inside. A can of liquid electrical tape is good to have to seal up the hole that you put in the insulation. Check the wire about every foot or so. When you press the continuity tester into the wire, it should light up. When you find the part that doesn't light up, you have found your short.

As for jumping the wire, you'll need to use a multimeter first to see if it is safe. When the car does have power check that black wire to see if it has 12v of power going to it. If it has less you may damage the coil by jumping it. If you do jump the wire, remember to disconnect it when you park, as it can both drain your battery and burn up your coil.
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Tuesday, August 7th, 2007 AT 10:49 PM

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