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Smartcraft Guardian at 3500 rpm. (2007 Sea Ray 290 SLX) 5.7L 350 Mag Mpi Bravo 3

S

Shaun M

New member
Boat has twin 5.7L 350 Mag Mpi engines. Port engine was removed and overhauled due to hydro lock last summer. Since installation port motor continues to throw overspeed alarm (Guardian) at 3500 rpm. New ECM, Water pressure sensor changed and pressure mechanically checked good. No overheat at all. Other than 3500 rpm limit the engine runs perfect. Could this be a neutral switch problem communicating bad information to the ECM? I'm at a total loss at this point!

Shaun M.
 
Chris,
This is not an interrupter switch is it? My engines don't have them. It has neutral start switches in the shifter housing. Just FYI.
 
Docksidemarineservices said:
There is a switch on the SB exhaust elbow and it is a shift event switch that tells the ecm that the drive is in gear and allows full RPM. If you do not have this switch, it is missing.

PN 808009T11

Looks like this
http://www.2040-parts.com/_content/items/images/14/624414/001.jpg
Click to expand...

Thanks Chris! That is the switch I referred to in my original submission. I do have that on my engine and I ordered the part yesterday. Thanks for confirming my suspicion! Fingers crossed!
 
Docksidemarineservices said:
What switch did you swap?
Your ECM is not seeing the shift event. Look for the purple wires on the engine by the Sb exhaust elbow.
Click to expand...

Thanks Chris! I swapped out the shifter switch that you recommended by PN and description (purple wires). It made no difference. Port engine is still throwing overspeed at 3500 rpm. I have noticed that Smarcraft says its the stbd motor overspeed on the gauge, but it's the port engine that causes it. Having spoken with Mercury they said I'm supposed to designate the port engine "port" through the software program because all engines (unless counter rotating) come designated as stbd engines. Could this be part of the problem? I'm replacing the pressure sensor again today just to be sure it's good, but I honestly don't think that's the problem. I'm at a total loss at this point.

Shaun
 
Could it be wiring problem between the shifter switch and the ECM? In other words, the switch is working properly but the information is not getting to the ECM? I would think I would probably have another type of warning or alert about that too! LoL!
 
Hi Shaun. Did you solve the issue? I have a Mercruiser 5.0 mpi , smartcraft overspeed alarm over 4000 rpm, temperature is ok. Thanks Martin
 
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