Just got off the phone with the shop...

[WhiteRice]

1997 Evinrude 25HP 3Cyl

Took it into the shop after trouble-shooting as much as I felt comfortable doing. Motor would not go WOT and would max out at less than 3000 RPM. Tried several things here with numerous recommendations from several members (thanks to those that gave me some input). Tech called me today stating he thinks the motor is overheating. He said the head looks ok but the seals between the head and head-plate were plugged (water flow) and the O-rings were getting replaced as well. Said parts were on order and would let me know later this week... (**edit** I have had a solid stream from the tell-tale every time this motor has been ran)

Here's my issue without trying to sound like I know more than the techs (which I most certainly do not). #1: If I was overheating, wouldn't the motor have an alarm / indicator light that would show this? #2: Wouldn't the motor go to a higher RPM and then limit itself if it detects a temperature issue? My motor will not go into WOT or higher RPM at all. I've read in my service manual that this motor does have the S.L.O.W. system and the oil injection system was removed prior to my buying this boat. Low Oil Pressure and Overheating will activate SLOW. Does the oil sending unit sensor plug need to have a jumper or something to keep the motor from thinking there is low oil pressure? This was not answered by the tech when I asked today.

 

[vroom ZOOM]

check out the cdi electronics troubleshooting guide, it has the info you need if it is an electrical issue

 

[WhiteRice]

I got the link from racerone a while back for the CDI guide. I don't have a way to diagnose the low oil sensor because it was removed with the oil tank. I was curious if the connector that was for the sensor needed to be grounded out or jumped to bypass any issues that may cause the motor to activate the SLOW feature

 

[Faztbullet]

(**edit** I have had a solid stream from the tell-tale every time this motor has been ran)

That's the water pump indicator...it tells you water pump is working and doesn't tell you anything about engine cooling.

 

[dingbat]

#1: If I was overheating, wouldn't the motor have an alarm / indicator light that would show this?

yes, assuming the temp sensor is good and the alarm system is working correctly.

#2: Wouldn't the motor go to a higher RPM and then limit itself if it detects a temperature issue?

Slow limits the max RPM. You will not exceed said RPM until the alarm is cleared.

Low Oil Pressure and Overheating will activate SLOW. Does the oil sending unit sensor plug need to have a jumper or something to keep the motor from thinking there is low oil pressure?

a 2 stroke doesn't use a pressurized oiling system, thus no oil pressure. Only oil tank level.

Continuous / Steady horn = Overheat (Two sensors one on each head - tan wire. You can check these, 1 at a time, by taking each connector apart and grounding them to the block with the motor OFF, but ignition key ON - you should hear the constant tone)

Constant Beep - Beep - Beep = No Oil (Wire connector to VRO)

Beep, Beep, Beep for 10 seconds, then Beep every 30 to 40 seconds = Low Oil

Constant / Steady horn @ >= 3/4 throttle = Lean Fuel Condition (This will also sound at much lower throttle/RPM settings if you try to accelerate when a lean condition exists - 2 wire connector on Vacuum switch)

 

[WhiteRice]

Thanks for the clarification dingbat. "Oil Level Sensor" is what I read in the service manual but just thought pressure for some reason. Thanks for the info. I have never had any alarms or any horns from this motor. Given I have only had it out three times since I purchased it but all three times it has done the same thing: Starts up fine, idles fine, shifts fine, will not throttle up past about 1/3 up on the throttle. Carbs thoroughly cleaned, timing checked, flywheel key in-tact, fuel system working fine... just no WOT.

So again... does removal of the oil tank and oil level sensor require anything to be done to the oil level sensor wire harness to bypass the motor from going into SLOW? Is my motor "thinking" there is low or no oil?

 

[dingbat]

Thanks for the clarification dingbat. "Oil Level Sensor" is what I read in the service manual but just thought pressure for some reason. Thanks for the info. I have never had any alarms or any horns from this motor. Given I have only had it out three times since I purchased it but all three times it has done the same thing: Starts up fine, idles fine, shifts fine, will not throttle up past about 1/3 up on the throttle. Carbs thoroughly cleaned, timing checked, flywheel key in-tact, fuel system working fine... just no WOT.

So again... does removal of the oil tank and oil level sensor require anything to be done to the oil level sensor wire harness to bypass the motor from going into SLOW? Is my motor "thinking" there is low or no oil?

Low oil is an alarm but not a SLOW (2,500 rpm) condition. Does the motor shake badly at the "limit"?

You need to make the diagnostics tests in the manual to see which alarm circuit is closed, if any. It could be something as simple as loose wire or worn insulation on a wire allowing it to short to ground. It's possible you have a bad power pack.

 

[WhiteRice]

Motor did not shake badly at it's peak RPM. It would troll just fine at idle (no wake speed) through the canals before I got to the open bay. Once I would try to open it up it would just not go any further in the RPM range about 1/3 of the way up on the throttle control. The remaining 2/3 of my throttle control would not do anything for the RPMs or speed and the motor would actually stall out with the control at the WOT position for longer than 30 seconds. The motor would start right back up without issue but the results would repeat itself.

 

[dingbat]

Motor did not shake badly at it's peak RPM. It would troll just fine at idle (no wake speed) through the canals before I got to the open bay. Once I would try to open it up it would just not go any further in the RPM range about 1/3 of the way up on the throttle control. The remaining 2/3 of my throttle control would not do anything for the RPMs or speed and the motor would actually stall out with the control at the WOT position for longer than 30 seconds. The motor would start right back up without issue but the results would repeat itself.

Since this motor is new to you, what size prop are you running? What size and make is the boat. It's quite possible the prop is too big for the boat

 

[oldboat1]

Did you or the tech do the usual tests for compression and spark? Drop cylinder test when won't throttle up?

 

[flyingscott]

There is another complete post on this motor. Make sure you and the tech test drive it before you pick it up and pay.

 

[WhiteRice]

dingbat: this is on a 16ft Carolina Skiff. It has a 4 blade 10.25" x 12 if I remember correctly (I may be wrong... will need to verify)

oldboat1: I checked these and spark jump was solid on all 3 cylinders with a tester and compression was 125, 122, 121. I have not personally done the drop test because I have been solo the times I have had the boat out. I was not in the position to pull plug wires while the boat was underway. I would hope that the shop would've checked the power-pack before diving into an issue with the head over-heating. Again... I hope :-/

flyingscott: thanks. Is there a solid way to test this before paying considering the shop does not have a lake? I was told they have a test tank but how much load does that actually place on the motor considering my issue?

 

[oldboat1]

just need a timing light hooked up where you can see it flash (or fail to flash).

 

[flyingscott]

dingbat: this is on a 16ft Carolina Skiff. It has a 4 blade 10.25" x 12 if I remember correctly (I may be wrong... will need to verify)

oldboat1: I checked these and spark jump was solid on all 3 cylinders with a tester and compression was 125, 122, 121. I have not personally done the drop test because I have been solo the times I have had the boat out. I was not in the position to pull plug wires while the boat was underway. I would hope that the shop would've checked the power-pack before diving into an issue with the head over-heating. Again... I hope :-/

flyingscott: thanks. Is there a solid way to test this before paying considering the shop does not have a lake? I was told they have a test tank but how much load does that actually place on the motor considering my issue?

If they have the correct test prop there should be no issue running it in the tank.

 

[WhiteRice]

Shop called back today. They fixed the head seals, O-Rings and water ports and it corrected the issue with the sensor thinking the head was over-heating and putting the motor into Limp mode. This celebration lasted for about 15 minutes :-/ He was able to open up the motor in a test tank, got it to 5200RPM and it was steadily cruising perfectly. That is until 10 minutes into its run it just shut down. Started right back up and ran it at 5200RPM and it shut down again after about 6 minutes. This kept happening until it would not start until it sat for about 5 minutes. Started it back up and the cycle repeated itself. He is now calling "powerpack" even after he said the unit was testing within parameters. He is saying it could be going into intermittent failure once the motor is heating up. With the works on the head, a new powerpack and diag fees, I am looking at $875. Can powerpacks "fail intermittently"? I don't feel this guy is trying to take me for a ride, but I have read of coils failing due to heat sensitivity... not a powerpack.

 

[dingbat]

Can powerpacks "fail intermittently"? I don't feel this guy is trying to take me for a ride, but I have read of coils failing due to heat sensitivity... not a powerpack.

Most, if not all electronic components are heat sensitive to some level. Some more so than others. Certainly could be the result of an overheating problem

 

[WhiteRice]

What really annoys me the most is that I never get a horn or light from an overheat issue when I had it out on the water with these symptoms. Kind of concerning actually...

I guess we will see come Friday when it's supposed to be ready. Planning on taking it to FL in 4 weeks for 8 straight days of fishing so I hoping all of this will be worth the peace of mind.

 

[jimmbo]

Could be as simple as a corroded connection, they heat up too when passing current. That's one of wonderful thing about electronic modules, sometimes the only way to verify they are good/bad is to replace. However, those parts are not returnable once purchased. Sometimes I wish these engines were using an old fashioned battery points ignition.

 

[flyingscott]

If that motor is a tiller you may not have a warning horn or light.

 

[hidef]

I had a similar issue as you with my 1996 35 triple. Engine basically stayed in slow mode. Ordered a New Power Pack and the issue remained. The ultimate cause was in the wiring harness. Ended up cutting the tan wire for the low oil / no oil warning at the power pack connector. There are two tan wires one is for the over temp and the other is for oil system. To see if it is the wiring harness you need to disconnect the connector with the tan wires if the motor runs with no issues there is your problem.