1998 Nissan NS9.8B stalls after 15 minutes

outerss

Cadet
Joined
Sep 20, 2016
Messages
6
This is a new problem which started the first time I brought the boat out this year. Engine starts just fine. Runs great for about 15 minutes (including idle), then just dies. Already checked the usual suspects, gas, plugs, and fuel line. I know it is getting gas, since I took the cover off, elevated the tank and watched until it quit. I also replaced the membrane in fuel pump which did not fix it. The engine will restart without any problem once it has cooled, but stops after it heats up again. I did notice that before it died the last time, it did billow some exhaust. Any suggestions?
 

outerss

Cadet
Joined
Sep 20, 2016
Messages
6
So I put a spark plug checker on it and ran it again. Seems like it is still getting spark even after it dies when cranking the starter.
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Could be a head gasket related issue on its way to become completely shot. Happened to me once and drove me crazy for a while. Now change head gaskets from time to time. BTW, a compression test will not show this kind of malfunction.

Happy Boating
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Clean well both matting crankcase surfaces, remove all previous gasket remains. Torque to specs with a torquemeter. Replace both plugs for new ones, gap to 1.0 mm tight. Take advantage to decarbon piston heads and cylinder head if too much carbon is found when opening crankcase. Report if solved the problem...

Happy Boating
 
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