2007 Merc 115 4 Stroke efi Limp Mode

[-Marc V-]

Hey guys, wondering if anyone might be able to point me in the right direction.  I have the motor as stated in the subject line.  As of late it's been going into limp mode after driving it for a little while.  Thought it was an over heating issue at first because the alarm and limp mode would only happen after running it for a period of time.  Like this morning, a buddy and I were driving across the lake, maybe a 10 minute trip, and the alarm came on and went in limp mode all the way back to the launch.  It has been stuttering during acceleration.  Not sure what was going on there.

After we ran it this morning checking out the motor putts with stuff, we put it back in the lake.  Ran alright at higher speeds, but still stuttered during acceleration and while at 3500rpm would have a stutter occasionally too.  Then after running it for a while it went back down to limp mode running pretty rough and only at slow speeds.

The impeller is streaming water just fine even at idle.  The water coming out is only luke warm.  The engine block even after running for a while is probably considered very warm to the touch but not hot.  I can put my hand on it and leave it there.  I have changed the thermostat as initially I thought it was an over heating issue.  

I've just changed the spark plugs, flushed the injectors and tested the coils, and all them seem alright.  Didn't notice anything alarming.  Put the muffs on in the driveway and it wouldn't go above 2k rpm and ran pretty rough at rpms above idle.  Idle seemed somewhat alright. 

In the two seasons I've owned it I've winterized it with Marine Stabil, and have only used ethanol free/non oxygenated gas.  The voltage also seems alright as when it's running the graph is showing it's producing 14.1 volts, or down to 13.9 depending how many accessories I have on.  

I really would rather not take it in.  I was quoted $115 for the first hour of diagnostics.  

Anyone have any thoughts??

Serial# 1B423334

Thanks!
Marc

Edited September 10, 2016 by -Marc V-

[Cheers]

The alarm is a code and will indicate the problem . Is it a series of beeps or a solid beep ? The alarm went of on mine this spring similar to yours . It was a steady beep that  indicated over heating . Had me stumped because the motor was pumping a water stream and the alarm would stop and start intermittently . Turned out to be that the water pump that I had gotten replaced a year or so ago (by a cheap back yard mechanic ) had not been properly installed and that seals where missing and replaced with silicone . The mechanic that repaired the motor the second time explained that because the pump was incorrectly installed, air was getting sucked in the lower unit resulting in poor cooling even tho the motor had a stream it wasn't properly cooling . I did also find that once the motor went to limp mode it would stay there until I went into neutral, even though the  issue was temporary  the computer would not clear its self

[-Marc V-]

Yesterday in the driveway it was one long beep.  Other times I believe it's been either 3 or 4 beeps.  I'll try it again today.  Are we able to plug these motors into a code reader like cars to get error codes?  The mechanic said that's not possible but given these motors can record hours at tom intervals would think they would have error codes. 

Yours was even streaming water like it should?  

[RebelSS]

Might help...

 

[ANYFISH2]

Change your oil!

[Cheers]

I am pretty sure the computer remembers the alarms just the same as a car

[-Marc V-]

The oil and filter were changed when i got it out of storage this year.  The oil level is in the normal range too. 

Edited September 11, 2016 by -Marc V-

[delcecchi]

Symptoms fit the "coolant sensor failure"    Runs bad since computer thinks motor is cold and makes stuff too rich.  Then figures out sensor is screwed up and goes to limp mode.   

You could replace the sensor and see. 

Could also be a thermostat stuck open, although I'm not sure whether that would cause limp mode. 

It looks like sensor is maybe 50 bucks.  

Edited September 11, 2016 by delcecchi