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Please tell me this is not as complicated as it sounds?

meatsfd

New member
i have 3 cylinder 1972 mercury 650 with cdi. I am not getting spark at the cylinder but if i move the same wire to the other 2 spark plugs i do. Its the same on all 3 wires. Why would it not spark on plug its suppose to fire?
 
i have 3 cylinder 1972 mercury 650 with cdi. I am not getting spark at the cylinder but if i move the same wire to the other 2 spark plugs i do. Its the same on all 3 wires. Why would it not spark on plug its suppose to fire?

with spark plug in wire it will spark to frame. the spark plugs are the ones that are flat. Does it ground on piston and its not close enough to spark. is something way off?
 
perform spark test one by one with spark plugs off to the cylinder insert it to their designated ignition coil and ground it to the engine block

Thay all spark to block. They just won't spark from wire to spark plug on correct cylinder. If I try same wire to different plug it sparks. So weird.
 
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perform spark test one by one with spark plugs off to the cylinder insert it to their designated ignition coil and ground it to the engine block

Thay all spark to block. They just won't spark from wire to spark plug on correct cylinder. If I try same wire to different plug it sparks. So weird. They are plugs like these. Does these plugs spark to the side of itself or does it spark to piston? The only thing I can think of is it sparks to piston and some reason piston isn't all the way up when it fires.
 
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The plugs spark to themselves across that circular gap. I suspect you have a water leak into the top cylinder. Seen that before.

Jeff
 
The plugs spark to themselves across that circular gap. I suspect you have a water leak into the top cylinder. Seen that before.

Jeff

No water. It's the same on all cylinders. #1 wire will spark to 2&3, # 2 wire will spark to 1&3 and #3 wire will spark to 1&2.
 
i have 3 cylinder 1972 mercury 650 with cdi. I am not getting spark at the cylinder but if i move the same wire to the other 2 spark plugs i do. Its the same on all 3 wires. Why would it not spark on plug its suppose to fire?

I would have to ask are you sure your wires aren't mixed up.Even though in my mind they should spark on all 3 regardless.
 
I quadruple checked wires, distributor belt alignment and all wire connections. It makes no sense at all.

Got to be your distributor cap did you look at inside for cracks.You might not see them anyhow ,there's a test for that somebody post back a bit . Look for a post on an 1150 thunderbolt wierd firing problems, or something like that.A guy explains a test for that and other firing problems.Not all of the test will be applicable with your motor,but I think the test for the cap and wires probably will. You may need help with that
 
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