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43L Merc sputtering

8

89renkin

Guest
"I changed the oil this spring

"I changed the oil this spring to both the engine and lower unit. Started up in yard and ran fine. I put it in the water a week later and it was hard starting, wouldn't stay running when put in gear, engine was idling rough. I finally got it started and running about 45 minutes later at the dock and ventured out to sea. About 2 miles out cruising at about 30 mph, it just died, sound like it sputtered first. Tried to restart but battery was dead and had to get a tow back. Now, back in the yard, put in a can of seafoam, recharged the battery, replaced the fuel/water filter, started it up and it doesn't stay running again. It seems that 1 out of 10 cranks, it runs okay and I can give it gas without it stalling, the rest of the time the engine shakes like it is ready to stall until it does (10 seconds later) or when I give it gas, I can hear gas spraying into the carb, (it sounds like air swooshing). Now I am also noticing a knocking sound coming from the lower unit, is this related? Should I check the distributor plugs, points? Not to mechanically inclined once past the basics. Thanks in advance!"
 
89 4.3L has Thunderbolt Elec.

89 4.3L has Thunderbolt Elec. Ign. Clean the spark arrestor and change the spark plugs; gap per the label on the valve cover. Guy
 
"Thanks Guy, Do you mean the f

"Thanks Guy, Do you mean the flame arrestor, if so, I soaked that in Kerrosine to clean it out when I changed the oil. I do this a few times a year. I will change the plugs and gap to .035" as suggested by the manual and try that. I bought the boat 3 years ago and haven't changed the plugs yet, so hopefully you are on to something..."
 
"I'd say that it is time f

"I'd say that it is time for plugs. Inspect each plug as you remove it. Each plug should be tan in color if it has been firing right with the proper carb gas/air mixture. Heavy carbon deposits can mean too many fuel additives and or spark wire breaking down. Black soot on the plugs means the mixture is too rich. Carb work needed as rod said; could be a simple choke adj. Did you clean/replace the carb fuel inlet filter screen?

Look under the dist. cap and inspect for carbon tracking and corrosion of the studs; replace if questionalble along with rotor. If the wires are original, consider replacing them if it still has slight misfiring. Look at the optic sensor that takes the place of the points. If it is heavily rusted, time to replace it. Last but not least, check the engine timing as specified on the VC lable.

Let us know what happens. Guy"
 
"follow up: I replaced the pl

"follow up: I replaced the plugs, (they were rusty and black), belts, fuel filter, checked the distributor, (noticed a hairline crack in the distributor, not the cap), added 2 + 4 fuel conditioner, let sit overnight. drained the fuel/water separator the next day and it started up and ran fine. I think I had bad gas in it. Although, I should replace the distributor, but that part is hard to find. Haven't looked at the points yet because it is running fine. Thanks for your suggestions and help and if you know where I can get a 986060 prestolite distributor, would appreciate it."
 
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