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Yanmar 8LV370 and ZT370 sterndrive loss of power issue

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peterbrown

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Hi, Just wondering if anyone has seen a similar issue

Currently we have an issue of losing power after an alarm has been activated
Vessel has 2 * 8LV 370 Series with ZT 370 SternDrive

Take boat for a 5 to 10mile cruise. All good
Idle back into marina, turning steering wheel to test steering and alarm goes off.
DriveECU detect Failure
Diag List – Rudder Angle Sensor Fault
Take boat out of marina to test and could not get normal power. Turned off engines and restarted but no change.
Revs increased but normal power just not there. It is like it is running on one motor, cavitating.
Props all look good. Tilt is down.
Took boat back at low speed.

This has happened twice now on two separate days.
 
I don't have any detailed Yanmar data...so this is just an educated guess....

Sounds like the rudder sensor has failed after the 'cruise' and when it happens the ECU goes into a power reduction mode....I'd start with the connector on the sensor to see if its loose....
 
We did think down these lines but what is confusing us is how the engine can give the normal revs but just a lot less power. Is that how their power reduction mode works?
 
Never experienced it first hand....usually, typically the ECU limits the injectors' output with a cap in the RPM, depending upon the level of reduction deemed appropriate.
 
peterbrown said:
Hi, Just wondering if anyone has seen a similar issue

Currently we have an issue of losing power after an alarm has been activated
Vessel has 2 * 8LV 370 Series with ZT 370 SternDrive

Take boat for a 5 to 10mile cruise. All good
Idle back into marina, turning steering wheel to test steering and alarm goes off.
DriveECU detect Failure
Diag List – Rudder Angle Sensor Fault
Take boat out of marina to test and could not get normal power. Turned off engines and restarted but no change.
Revs increased but normal power just not there. It is like it is running on one motor, cavitating.
Props all look good. Tilt is down.
Took boat back at low speed.

This has happened twice now on two separate days.
Click to expand...
Had a similar problem today. Did you get to the bottom of it?
 
Sadly people report problems but not the solution. My guess was water or moisture in the bildge. Corroded contacts, loss of signal to drive ECU and u have full story to read. Each time i inspect the boat i start with signs of water or moisture and what it can do. Checking wire harness and any signs it was submerged even temporarily etc. If all contacts are good and ECU locations were not exposed to wet water moisture etc i proceed to mecanical things
 
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