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spark jump

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BurninDiesel

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hey guys i just bought a new boat well new to me with a 05 350 crusader in it and i am have a spark problem.. the boat runs great for about a hour or so then i start losing spark in random places out of the coil, in the middle of the distributor, the spark will jump threw the coil wire to +??, ive changed the coil and coated connections with rtv and changed spark plug wires, cap and rotor and I still have the same probelm. Could it be resister? o yeah i aslo change the ignition module. Thanks for any input
 
Excessive spark plug gap? Something is making it very difficult for the spark to jump the plug gap. so it's jumping at the cap instead.

Jeff
 
Ayuh,.... I agree with Jeff,....

Sparking at the coil says there's too much resistance downstream from the coil...

Bad spark plug wires, or bad spark plugs...
 
3X on the plugs...time to check them out.

RTV on the connections - time to shoot the source of that idea. You want to use a good silicone dielectric grease on the ends of the high tension leads, never RTV. you also need to make sure both ends of each high tension lead get seated completely.

It's also possible to have a bad set of wires right out of the box (not common but it does occur). Its not that big of a deal to verify each lead with a good digital meter before you install them.
 
Mark is right no RTV on the connections, when dry RTV is an insulator not a conductor of electricity,as he said they need to be coated with a good dielectric grease. This could definitely be some of your problem,clean everything up and start from scratch then check the plugs. Electricity acts just like water...they both take the path of least resistance . If the spark is jumping everywhere before the plugs then there's a problem between the distributor and the plugs. Its easier for the spark to reach ground the way it is doing than go thru the plugs......Good luck , Lee
 
Dielectric = insulator. The grease will 'seal' the connections from the elements to help maintain the integrity of the spark while allowing them to be separated, as needed. RTV doesn't have the dielectric strength (so it will 'leak' high voltage) of the grease and is designed to bond, not slip. The other issue is that not all are 'pure' which will only multiple these issues. "Clean" is a good mantra for the secondary side of any ignition
 
well I pulled the pulgs and noticed one of the plugs was cracked so i changed them with acdelco iridium plugs and that fixed the problem.. I didnt change them before becuase the previous owner told me he just changed them and I realized that he had used the wrong plugs with the wrong temp rating thats why i think that the boat would run good for about a hour or so until it got good and warm and thats when the problem would occur.. I put dielectric grease on the plugs, i just put rtv around the coil boot trying to prevent it from jumping out.. Thanks guys for all the feedback and help
 
From what you're saying, you never had a spark jump problem; what you had was massive preignition caused by plugs running way too hot.

I hope you didn't damage your engine>

Jeff
 
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