[cp4000]

I have been fighting that for years now. My brand new exhaust was sagging causing the fumes to get into the cabin and setting off my detector. Have that all fixed but still get it coming over the sides when fishing if the wind is blowing at me and sometimes when underway due to the vortex created behind the boat. I have installed new carbs, had them professionally tuned twice, installed K&N flame arrestors, HEI ignition and still does it. A few things that I have heard lately...May have to run a 10ga wire from ignition to HEIs. Make sure flame arrestors are clean. Plugs are good and gapped properly. I may just go with fuel injection. I heard around $2,500 a side.
Please let me know if you discover anything.