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Ask Dominick Your Own Question
Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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I have a 2001 mercury optimax 225 i am having intermittent

Customer Question

Hi I have a 2001 mercury optimax 225 i am having intermittent power reduction where rpm temporary drop from 4200 rpm to like 3500 and then bounce back - I have checked water separator and now water in fuel, I am getting no alarms
Submitted: 1 year ago.
Category: Boat
Expert:  Jeff G. replied 1 year ago.

What is your max rpm?

When it drops rpm does it stay there or does it come back, then does it drop again?

What is the serial number of the engine?

Customer: replied 1 year ago.
Hi JeffSerial # ***** ***** - production # ***** - The RPM drops and then comes right back, it usually happens after running for 30 minutes or when I hit rougher water. I am not sure of maximum rpm I think its 5500. Engine runs good and strong when the RPMs are not bouncing.
Expert:  Jeff G. replied 1 year ago.

So the rpm's are bouncing not staying a a lower rpm? Is this a new symptom or something that has been happening?

Customer: replied 1 year ago.
Yew It's been happening for about a month I'm thinking something electrical
Expert:  Jeff G. replied 1 year ago.

Let me check service bulletins and look a few things up. I'll post back as soon as I can.

Customer: replied 1 year ago.
Okay thanks I am going to put on rinda scanner tomorrow
Expert:  Jeff G. replied 1 year ago.

See if you can run with the scan tool on the engine.

Customer: replied 1 year ago.
I put the scanner on it, I wasn't able to get out on the water and run it under throttle, I got 3 fault codes while idling - 2 I understand I can ignore Sea Temp ckt, and Fuel Level ckt, the third not sure bit it says Oil LVL Ckt HI - I did by the way have the oil tank on the engine replaced in June because the sensor or float or whatever was bad.
Expert:  Jeff G. replied 1 year ago.

Do you have any alarms or a Smartcheck gauge?

Customer: replied 1 year ago.
no smartcheck gauge nor any alarms, I'm going out on it today if it starts loosing power with RPM fluctuations (which it has on almost every trip). i will try to record the ecu data with the rinda software. I will also keep an eye on the voltage to see if it drops.
Customer: replied 1 year ago.
Hi JeffI had an improper battery (actually 2) in the boat they each had 650 cca deep cycle/start - I changed one of them out yesterday to a proper 1000 CCA starting batter. I have read that the wrong battery would cause the type of power fluctuations I am experiencing, could this have been the problem ? I don't understand why this would cause power issues because I thought once the boat was running over 650 rpm the power would come from the alternator
Expert:  Jeff G. replied 1 year ago.

The power comes from the batteries all the time, same as in a car. But the alternator is to provide enough charging voltage to keep everything running

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