225 EFI alarm buzzer at WOT

[bep078]

I have a 2006 mariner 225 EFI with bobs 4" hydraulic jack plate. The boat is European so i highly doubt that anyone would know what it is. When the engine is at WOT (73mph @ 5750 RPM) all of a sudden, the alarm is heard and a warning on the smartcraft gauge displays ''reduce throttle''. I then stop, put the engine in neutral and the alarm and warnings stop. The temperature and water pressure remain constant at wot. What could be the problem? could it be perhaps that the engine is over revving or perhaps the water pickups are out of the water and picking up air? the jackplate is set at its lowest height as if i were to increase the height of the jackplate, the alarm would go off quicker than if it were to be lower, again, temperature and water pressure are always constant. :confused:

[hotbeek]

Probably rev limiter

[hotbeek]

What pitch prop are you running ? try a higher pitch. 5800 is a common rev limit barrier.

[bep078]

The prop is a tempest 26". Im about to try a Chopper 26. Would this make a difference? is there a way of removing the limiter?

[hotbeek]

You'd have to have your ecu's recurved. Usually ignition ecu will start to retard timing and fuel ecu will richen up.

I'm not sure how the chopper will run as far as rpms but if you find something that will run a hundred less rpms you'll be alarm free(if it's a rev limiter alarm) You could have your 27 worked to pull less rpms.

[bep078]

Could it be that the water pickups would slightly be higher than the water and maybe there would be air in the water pump so the alarm would go off? The alarm is constant i.e. no cuts, just one long beep until the throttle is set to neutral.

[hotbeek]

I don't know the "smartcraft" gauges but I would think "reduce throttle" would be an over rev more than anything. If temp and pressure gauges look fine at speed I doubt there's a problem there. The higher jackplate setting would allow you to hit your rev limiter earlier thus the early alarm. If your plate is full down and still experiencing these alarms I don't think it would be from lack of water or pressure or air intake.

What type of hull do you have ? V-hull ? Where is proshaft in relation to bottom ?

[bep078]

it is a V hull. Propshaft is below the bottom when jackplate is set fully down. The alarm sounds also when jackplate is fully down. So it must be the rev limiter. Tomorrow i am going to try a 26 trophy, hoping to reduce rpm at wot to see whether the alarm would sound.

[hotbeek]

Do you know how much the boat weighs ? I run a 21' Checkmate Pulsare(v-hull) 1900 lbs(motor included) I had a stock 225EFI. I would just hit the limiter with a Trophy Plus 25. I would imagine if your boat is any where close to mine, the 26 should put you right where you want. I would try some different jackplate settings and trim settings. I bet you'll like the lowend punch of the Trophy prop. It may be 1-2 mph slower than a three blade but it's a fun ride !

Good Luck !