Suzuki / Johnson 140 check engine light

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Dustinfish

Seaman Apprentice
Joined
Aug 9, 2011
Messages
46
Moving this over here from the Johnson form because of this almost being a suzuki engine. It is a 2003 140hp johnson. I am about to go crazy with this check engine light. I get the check engine light ONLY when in the water after about idling for about 3 min. Its a 3-2 blink which I understand is a map sensor 2. When I bring the engine on land and run it with the hose, problem goes away. Now it has gotten to the point where the engine wont even start in the water but will start on the hose. Please any ideas let me know.
 
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Dustinfish

Seaman Apprentice
Joined
Aug 9, 2011
Messages
46
Re: Suzuki / Johnson 140 check engine light

Do you guys think this has anything to do with pressure on the exhaust some how bogging the engine down in water? I will get a trash can tomorrow and try to comform this. This is the only difference I can see with a boat being in the water.
 
9

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
8,878
Re: Suzuki / Johnson 140 check engine light

putting it in the water does cause more back pressure on the exhaust , but I do not understand why that would cause a sensor code to fire.
Make sure you have good compression an all cylinders and check out the sensor if you are getting a code on it.

I believe the MAP gives the computer the atmospheric pressure the motor is at (altitude) so that it can determine the proper fuel to air ratio and will cause problems if not right. My guess anyway
 
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Dustinfish

Seaman Apprentice
Joined
Aug 9, 2011
Messages
46
Re: Suzuki / Johnson 140 check engine light

Think when a sensor goes bad, its goes bad all the time so I dont think that can be the problem. Starting to think I have a large amount of carbon build up in my engine limiting the amount coming out. Thus getting back flow and forcing the engine to shut down or bog down. Does anybody know any good carbon / fuel injector cleaner? I have heard that Amsoil was pretty good.
 
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