2007 Yamaha 40BEJR

[Drw56371]

I have a Yamaha 40BEJR 2007. I am trying to diagnose a new problem.
1. At about half throttle(just before the boat come on plane) the motor seems to lose loose power and the sound of the motor changes to a deep rumble at the same time. 2. After I throttle past this stage to full throttle the motor seems to pulse and vibrate. I am a full time fishing guide but not a mechanic by any meens. I do run my motor every day and so I can definitely tell that this is a new problem and that is it running differently. Any help or suggestions will be greatly appreciated. Thank you

[99yam40]

does this motor have an alarm system?
and is it working properly?

[Drw56371]

Yes it does have an alarm system. I believe it is working properly although maybe it isn't? It will go off if I suck in leaves or grass

[99yam40]

test it by grounding the pink wire on the temp switch on the head with the key in the on position or drain the oil tank to see if alarm sounds

fuel pump leaking into the crankcase will stop the #3 cylinder from burning (firing properly)

[zenoahphobic]

I have a Yamaha 40BEJR 2007. I am trying to diagnose a new problem.
1. At about half throttle(just before the boat come on plane) the motor seems to lose loose power and the sound of the motor changes to a deep rumble at the same time. 2. After I throttle past this stage to full throttle the motor seems to pulse and vibrate. I am a full time fishing guide but not a mechanic by any meens. I do run my motor every day and so I can definitely tell that this is a new problem and that is it running differently. Any help or suggestions will be greatly appreciated. Thank you

Rumble, vibrate sounds like out of balance failed bearings etc.

Check your flywheel for looseness and check your propeller for the same including for bent broken blades.

It may just be the choice of words, something to do with fuel flow instead.

[Drw56371]

Hey I just realized that I forgot to put an F in front of the BEJR on the model number. So my motor is in fact a 40FBEJR. Not sure if this would make a difference in diagnostics. I will check every thing you guys have suggested. Thanks for the help