No spark

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Kansas, USA
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Can't wrap my head around this... Last year had to replace the head on the Focus, got it back on the road in November. I did reuse all the spark plugs since they were new. All was good till March this year, whenever it sets or rains it will not start. This time all the spark plugs but #3 was wet. #3 was a spark plug from a prior change couple years ago. I found another from the same change and went through and checked spark on all four wires with this spark plug, placed it on the edge of the valve cover. Spark on all four cylinders with that spark plug. Next was testing each plug. The plug from the other change sparked right away on the valve cover. The 3 other newer plugs didn't initially fire on the valve cover so put them on the radiator support and then they fired there and then they fired on the valve cover, I think the only difference is the new ones are double platinum's the older ones are regular platinum's. Both Motorcrafts. Interesting to see the spark along the electrical path. So I put all the spark plugs back and it fired right up, misfired some but finally cleared up. It'll probably run for weeks without issue now. I can't find the other two older plugs or this would be simple. I hate throwing parts at this thing but is it as simple as spark plugs? Just seems odd. I tried another coil, tested the wires before my help came home and still wouldn't start, compression is good since I know that'll be asked.
 
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Originally Posted by atikovi
Originally Posted by SOHCman
wet with oil or fuel?
Since he says the problem is during rain, probably water.
Fuel and if it sets or rains, but not every time with either.
 
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857
Location
Alberta
Change the wires. I had an old ex-police caravelle in my youth that would misfire in the rain. Opened the hood on the side of the road during one of these episodes and "wiggled things". Shocked the life out of myself when my arm brushed the wires in that damp air. They may look fine, but if they're breaking down, they show first in the wet.
 
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5,651
Location
Iowa
Pull the coil pack and closely examine for cracks. Look everywhere - around the towers, the sides and the potting underneath.
 
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4,165
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WA
Originally Posted by Eric Smith
Originally Posted by atikovi
Originally Posted by SOHCman
wet with oil or fuel?
Since he says the problem is during rain, probably water.
Fuel and if it sets or rains, but not every time with either.
Are you sure it's not coolant? Maybe the new head gasket didn't seat properly. Are you getting white smoke from the tailpipe or loss of any coolant? If you're 100% certain it's just plain water I'd look at the tube seals and boots. Water/coolant could cause your misfire and smell of fuel on the plugs.
 
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Originally Posted by kschachn
And if it's coolant you can smell it in the exhaust. You won't die from a quick sniff.
Right.. generally you know if it's coolant; smell/white smoke. That leaves what, water?... only one way that I know of water can get into the combustion chamber and that's via the plug bore. (I suppose you could pull moisture in via the intake but dang.. you'd have to have it practically raining under the hood for enough h20 to get drawn in to cause a misfire wouldn't ya?)
 
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No white smoke or the smell of antifreeze at the exhaust. But it is losing a small amount of coolant somewhere, you can smell coolant under the hood on occasion, but it seems to hold pressure for a long time. I did go ahead and put new Autolite plugs in last night, the same design (single platinum's) as from the factory. The motorcrafts have changed design to finewire. She drove it today and said it had a lot more power, she's been complaining about lag for a while. Time will tell. Thinking back it did drop the valve seat not long after I put those finewire plugs in.
 
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WA
Originally Posted by Eric Smith
No white smoke or the smell of antifreeze at the exhaust. But it is losing a small amount of coolant somewhere, you can smell coolant under the hood on occasion, but it seems to hold pressure for a long time. I did go ahead and put new Autolite plugs in last night, the same design (single platinum's) as from the factory. The motorcrafts have changed design to finewire. She drove it today and said it had a lot more power, she's been complaining about lag for a while. Time will tell. Thinking back it did drop the valve seat not long after I put those finewire plugs in.
A small amount of coolant disappearing might be nothing. But if you're seeing a noticeable disappearance of coolant and a smell of coolant in the engine bay, that coupled with the head repair job not long ago would point me to a head gasket leak. It could be just enough to throw off combustion but not show up at the tailpipe. Test your coolant for combustion gasses (you can buy the test kit on Amazon for not that much) and/or send off a UOA to see if there's coolant in the oil. Make sure you let the lab know what you're looking for.
 
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