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Author Topic:   2000 Mercury 225-HP EFI Lost Power
JohnL posted 08-13-2011 12:21 PM ET (US)   Profile for JohnL   Send Email to JohnL  
Last weekend I was coming in from crabbing when I noticed and felt a decrease in [engine speed of] 300-RPM [on a 2000 Mercury 225-HP EFI outboard engine]. I was near home so not a huge deal; I slowed down, let [the Mercury 225-HP EFI] idle, then tried to accelerate to plane. At this point the [Mercury 225-HP EFI outboard engine] would not [accelerate to] 4,000-RPM and [the boat] could not plane. The fuel level in the boat was the lowest I have ever let it get, so I figured I may have picked up some [debris] from the bottom of the tank. The next day [the Mercury 225-HP EFI] ran a little rough to start, but then worked like a champ.

Yesterday I made the two-mile run to the gas dock. By the time I got there [the Mercury 225-HP EFI] was acting worse than ever. But what I started to notice was when I trimmed the motor, it would get better. Like the act of putting some strain on the electrical system made it better.

After getting fuel [the Mercury 225-HP EFI] would idle just fine, but would not go at all. I turned the motor off and switched to battery 2 from 1. Problem went away. This motor also eats alternator belts--has since day one. A cheap stamped pulley is to blame. I know that for most of the trip back the belt was intact as I was noticing the most charge than ever before coming out of the motor.

I have replaced the belt and this morning [the Mercury 225-HP EFI] is running poorly on any of the three battery positions. [Do readers have] any idea what is going on? Is it okay to run this motor? Am I doing more harm?

I have a feeling the charging system is broken. I have planned to test this by taking off the [alternator drive] belt and seeing if the problem goes away.

I would love to be able to run the boat thru September as the fishing season here in Seattle is just starting.

Any ideas would be great. Thanks for your time.--JohnL
1998 Outrage 23
(yes the motor is a 2000)

Tom W Clark posted 08-13-2011 04:04 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
I turned the motor off and switched to battery 2 from 1. Problem went away.

John -- That would suggest there was not enough electrical power to allow the motor to operate properly.

There may well be something wrong with your charging system and the fact you have to keep replacing alternator belts reinforces this notion.

But I fail to see how removing the alternator belt entirely could possibly make "the problem goes away." It will only guarantee the batteries are not getting recharged.

When the problem occurs, what is the battery voltage as shown on either a dedicated voltmeter or on any one of your electrical instruments? (Most depthsounders, chart plotters, RADARs have a voltmeter function you can pull up.)

JohnL posted 08-13-2011 05:50 PM ET (US)     Profile for JohnL  Send Email to JohnL     

I will check my chart plotter for this function, Or go buy a voltmeter. My thought was that perhaps my alternator is overcharging?

More soon.


JohnL posted 08-13-2011 11:54 PM ET (US)     Profile for JohnL  Send Email to JohnL     
When the problem occurs the voltmeter, says the system is putting out 14.25 to 14.31. So at this point I have not idea what is going on.

Again what makes me scratch my head is why when I activate the trim button the [engine speed] starts to go up? Makes no sense. I tightened the connections, checked the batteries physically; all looks good. At this point I have no idea, but in the morning I am going to take the belt off and see what happens. I know the batteries won't charge, but I can charge each night when I get back in. I have a two-battery system, and this happens on A, B, or Both. And then, what is strange, when I turn the motor off and change batteries, it runs fine, until I idle, like in between pulling crab pots.

More ideas welcome, I will try the belt thing and report back in the afternoon.



jimh posted 08-14-2011 08:47 AM ET (US)     Profile for jimh  Send Email to jimh     
There are voltmeters in electronic accessories like a SONAR, but in general I would not trust them to be accurate. The best indicator of the battery voltage is a measurement made right at the battery terminals using a voltmeter with known accuracy.

If you are measuring 14.5-Volts at the battery terminals when the outboard engine is running, this is a reasonably good indicator that the outboard engine charging system is delivering charging current to the battery. Typically a 12-Volt storage battery will not have a terminal voltage above 12.9-Volts unless it is being charged by an external charging source. The presence of this higher voltage indicates that the charging circuit on your outboard engine is probably operating properly.

You report that there is a change in the outboard engine's running characteristics after you operate the TRIM motor. One possible explanation for this could be that operating the TRIM motor causes a relatively high current to flow, around 20-Amperes or more. Also, the TRIM motor is an inductive load, and when the circuit is made or broken there will be a high-voltage arc, much higher than 12-volts, from the inductive nature of the motor. The arc and the flow of a high current may be helping to re-establish an electrical connection in the engine which is otherwise not a good connection. When the TRIM motor current flows through the connection, the connection is re-made by the current flowing. The arc in the circuit will also jump across any insulation that might be formed which is otherwise preventing current flow or creating a higher than normal resistance in the circuit. Based on this deduction, I recommend you check the battery negative connection to the engine block. Also check any other electrical connections where there are several conductors being joined under a single terminal post. This is often seen in the primary power distribution under the cowling of outboard engines.

Tom W Clark posted 08-14-2011 11:10 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
Oh! I like Jim's reasoning, it is excellent. As with so many problems, it is often something very simple. Like Jim, I suspect there may simply be a poor electrical connection, perhaps at the battery terminals themselves.

I would start at the batteries and remove, inspect, clean and reinstall the positive and negative cables to the battery terminals.

John -- Were you pulling pots off the North end of Bainbridge yesterday?

JohnL posted 08-14-2011 07:38 PM ET (US)     Profile for JohnL  Send Email to JohnL     
Jim, Tom,

Thank you I will start going through the system.

As far crabbing, I am off of Possession Point on Whidbey Island. As most parts of the Sound crabbing has been excellent this year, frankly the best I have ever seen.


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