1985 Mariner 150 fouling plugs

TBird69

Recruit
Joined
Mar 14, 2012
Messages
3
The engine runs great the first 1 or 2 times taking it out but let it set and it will foul the plugs. Like today taking it out with new plugs again after the first time of it fouling the plugs and it runs great, stopped and fished for a hr cranked it up with no problem, moved and fished for another hr and again crank it up with no problem. Ran it down the river for a while then pulled back in at the dock and sit there about 15-20 mins talking, but when I went to crank it to pull it on the trail it fouled the plugs. Oil injection has been disconnected and I premix the oil/gas and run 100% gas. As I said it had new plugs, wires and the carbs have been rebuilt and float settings have been rechecked after the first time it fouled the plugs. New gas lines from the tanks to the carbs and new thermostats any ideas?
 

enginepower

Petty Officer 1st Class
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Jul 5, 2014
Messages
260
What ratio do you mix? Possibly engine running too rich? Possibly low compression?
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,646
Check the fuel pump diaghram. If they leak, raw fuel will be introduced into the crankcase. Spark plugs should never foul, if engine is operating properly.
 

Dukedog

Captain
Joined
Oct 6, 2009
Messages
3,509
Whats already said but will add "bleed lines, fittings" plus idle timing............One thing that might help while your chasin' tha problem is always keep tha motor trimmed at least "level" or a touch positive in idle...........It helps with tha "puddled" fuel.
 
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TBird69

Recruit
Joined
Mar 14, 2012
Messages
3
50/1 mix, compression is great, diaphragm is ok, all fuel lines new. The way it is doing we are starting to think it's something about the electronics/coil/stator getting hot and breaking down which might explain why it ran ok after sitting for a hr each of the 2 times we stopped to fish and only had a 15-20 min time to cool down at the dock ideas about that possibility?
 

TBird69

Recruit
Joined
Mar 14, 2012
Messages
3
Had the inside power pack (the one closest to the engine) going bad or I should say the last time we tried it the thing went out totally.
 
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