2003 70hp issue

[mystic122468]

Hey guys, I have a 70TLRC (freshwater) That i'm having what I think is an ECM problem..

Here is what's going on:
Engine starts and idles fine, throttle response is great when Not put into gear. When I leave the dock The engine doesn't seem to have full power, it will run 3 or 4 minutes then the BUZZER goes off and the engine retards and can only idle back at the dock, (anything above idle the engine sputters and shakes).. On One of the test runs it ran Prefect, came up on plane and the RPMs sounded great, only lasted about 30 seconds then back to running like the timing was electronically retarded. It's running around 170 degrees and over 13 Volts.

What I've Done:
New plugs, New Fuel Pump, New Fuel Filter, New Thermostat, New Voltage Regulator (Wasn't Charging), All 3 Carbs disassembled and Ultrasonic Cleaned, Timing checked, All 3 Coils Checked.

To me it feels like the ECM is failing and not letting the engine advance..

The Voltage gauge on the dash in not working but i'm showing 13+ at the battery when running

Any help from this point would be great!

Thanks in advance..

[brian3006]

So the buzzer going off is telling you that there is a problem. That is what is putting the motor into rpm reduction mode. If you have yamaha gauges, they will illuminate a light to tell you if it is an oil or temperature alarm.

based on what you describe, and the fact that you say it is running 170 degrees....I would look at an overheating issue. I believe the overheat alarm is triggered at 180.

where and how did you get this temperature reading?
Have you ever replaced the wwater pump/impeller? if so when?

[mystic122468]

So the buzzer going off is telling you that there is a problem. That is what is putting the motor into rpm reduction mode. If you have yamaha gauges, they will illuminate a light to tell you if it is an oil or temperature alarm.

based on what you describe, and the fact that you say it is running 170 degrees....I would look at an overheating issue. I believe the overheat alarm is triggered at 180.

where and how did you get this temperature reading?
Have you ever replaced the water pump/impeller? if so when?

The Gauge on the dash of the boat is where i'm getting the temp reading. I have never replaced the water pump/impeller.

Question: wouldn't the boat run perfectly until the "over heating" condition was triggered? it runs okay, but not at optimum RPM and Not on plane..

[ausnoelm]

Lots of stuff going on here, first off, don't just stab and hope, do you have any lights on the gauges to indicate an oil or temp alarm? They are the only thing that will trigger alarm and RPM reduction! Forget the ECU/power/CDI pack or whatever you want to call it! Your very first thing is to determine what the issue is, heat or oil, is the oil tank full? Does the motor feel hot to touch?
edit....revving it in neutral proves nothing, don't do it!

[mystic122468]

Lots of stuff going on here, first off, don't just stab and hope, do you have any lights on the gauges to indicate an oil or temp alarm? They are the only thing that will trigger alarm and RPM reduction! Forget the ECU/power/CDI pack or whatever you want to call it! Your very first thing is to determine what the issue is, heat or oil, is the oil tank full? Does the motor feel hot to touch?
edit....revving it in neutral proves nothing, don't do it!

There are no lights on the dash, only gauges. the Temp gauge is working and it fluctuates from about 120 to 170. The oil bottle is full and and I see oil at the carbs when the engine has been sitting.
It engine does seem hot to the touch and the stream of water that is coming out of the engine is warm but not Hot to the touch.

[brian3006]

If you have Yamaha gauges. the lights will be on the gauge itself.. such as this one...https://www.amazon.com/Yamaha-Outboa.../dp/B005CXL1UI

It will have a flashing block above one of the two lower icons. telling you which one is causing the alarm.


Are these the gauges you have or do you have an aftermarket type?

[mystic122468]

If you have Yamaha gauges. the lights will be on the gauge itself.. such as this one...https://www.amazon.com/Yamaha-Outboa.../dp/B005CXL1UI

It will have a flashing block above one of the two lower icons. telling you which one is causing the alarm.


Are these the gauges you have or do you have an aftermarket type?

They are aftermarket gauges, analog..

[99yam40]

telltale does not normally get hot anyway, it is just an indicator the pump is pumping.
need to find out what is setting off the alarm and then find out why

[ausnoelm]

telltale does not normally get hot anyway, it is just an indicator the pump is pumping.
need to find out what is setting off the alarm and then find out why

This just about covers it, changing plugs and regulators and all that kind of stuff is irrelevant, your very first task is finding out which of the two are causing the alarm, oil or heat, nothing more, nothing less......yet!

[mystic122468]

This just about covers it, changing plugs and regulators and all that kind of stuff is irrelevant, your very first task is finding out which of the two are causing the alarm, oil or heat, nothing more, nothing less......yet!

It appears to be heat related, I'm going to install a new pump and flush the engine..
Question: wouldn't the engine run perfectly until the alarm sounds? It seems to not hit full RPM or come on plane at this point.

[panasonic]

It appears to be heat related, I'm going to install a new pump and flush the engine..
Question: wouldn't the engine run perfectly until the alarm sounds? It seems to not hit full RPM or come on plane at this point.

That is a good question. My answer is maybe or maybe not. You may very well have two problems going on at once which makes matters worst. As said already you need to figure out what is setting off the alarm first! Once that is sorted out then move on to the low power issue before the alarm goes off.

[ausnoelm]

You have tinkered with lots of unrelated bits and pieces, you may now also have a self inflicted fault, the carbs bing "cleaned" might cause your low power issue, fooling around with the electrical system might also introduce issues, so far, you are no closer to saying yes/no to oil or temp.

[99yam40]

when I 1st got my C40TLRX back in 2008 I went thru the carbs many times trying to figure out what was all wrong with it.
once I found a small thin sheet of ,I guess dried up fuel residue in a carb bowl that would cover up a jet from time to time.
Guess it came from the fuel pump or one of the lines.

I did finally figure out someone had drilled out the main jets,so I replaced them and it ran fine at WOT finally.

I also found the CDI was not correctly handling the idle timing, when I adjusted it to correct specs then the WOT timing was out of wac.
I ended up replacing the CDI.
the thing is you will have to do some testing to see what is going on.
compression is easy to test, and it is very important.
so is timing and spark with a timing light hooked up to the individual plug wires.
correct fuel to air ration to burn properly is not so easy.
could be too little fuel or too much

BIL's 50 had a problem with bogging down but idled fine, I found #3 carb had the main jet was partially plugged.
thinking the carbs are clean is not always correct, cause hidden trash can hit a clean carb and cause problems

[mystic122468]

Installed a new pump and housing, no more buzzer.. However, it still doesn't seem to be at full RPM. Is there A special tach for a 3 cylinder so I can be more accurate?

[brian3006]

The number of cylinders itself does not make a difference for a tach. however, there are some older style tachs that have "pole settings"

what are you measuring RPM with now? What RPM are you getting while the boat is in the water moving at Full Throttle?
also, since you say the carbs were disassembled and cleaned, check all the adjustments and linkages and verify that the throttle butterfly is opening fully to a horizontal position.