Thread: Sooty Plugs
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Old 08-08-2019, 10:21 PM
SubtoSail SubtoSail is offline
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Sooty Plugs

Experts,

I'm almost ready to throw in the towel and mount an outboard, but not quite yet. I'll give the life story...to start shes a 1970 late model, mechanical fuel pump, EI, raw water cooled.

I'm having some reliability issues that I've been chasing for awhile now, and I thought it was all related. I've had the boat for about a year and a half, mostly trouble free. She wouldn't start to get us into our new slip on our maiden trip, replaced the spark plugs and she was running. Next trip she died, in response I rebuilt the carb with new jets, and replaced the fuel filter. Trouble free for about a year.

Fast forward, we get put back in the water after a haul out, she took a few more turns to start than normal, but she starts. We start the trip back, find that we're in over our heads and decide to motor, but she won't start. Replace the plugs and she starts, but dies after about a minute. We get a tow.

Discover that in our desparation we flooded the exhaust. At least there is a procedure for this. Drain the exhaust, change the oil 5 times, MMO the cylinders, clean the carb, compression check. Cold: 100, 70, 85, 100, warm: 100, 100, 115, 115. Shes running, let her go in the slip for an hour, throttle, idle, forward, reverse. We motor for two hours to get to our own marina. The last twenty minutes she starts to lose power. Felt like a cylinder shut off, more throttle and it comes back. Happens three times, eventually with full throttle she dies. We get a push into the slip, and she starts up.

At this point I think fuel problem, so I replace the filter, rebuild the mechanical fuel pump with the moyer kit, add the in line polishing filter, clean the carb, and replace the coil for good measure. She runs fine for an outing or two, then while pulling out of the slip she died as soon as I put her in reverse in idle. She would run with gas, just not idle. I found I had the adjusting screw 3.5 out, set it to 2.5 and now she's fine.

All four plugs are still sooty, and I believe this is all somehow related. I just took the exhaust apart, thinking blockage. Unfortunately, it all looks clear, not the best design in terms of height, but there does not seem to be a blockage.

Call me paranoid, but even though she starts up and runs right now, I don't trust her. The plugs are still fouling, which makes me say back out the adjustment screw, currently at 2.5 out. Any more out and she dies. I could remove the fuel and tank for cleaning, but she seems to be getting consistent fuel without water. All i have done on the ignition side is replace the distributor cap and coil. Could this be a timing issue?

The boat is just about 50 years old, and only used for day sailing. An outboard is looking more and more attractive.

Thanks for the help you have all provided so far!
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