1998 25HP 3 cylinder Power/ Ignition issue?

[JJGulley]

I have a 25HP 3 cylinder engine that we have owned since new. We have never had a single issue with this engine except the initial start up after sitting for the winter. Once it runs once, it's good for the season. Anyway we have got the boat back into the water up at the cottage and the engine starts right up when cold and runs great for the first 20 minutes or so. I can get to a location to fish, shut it down and then restart after a half hour or so. At this point I cannot give it more than 1/4 to 1/3 throttle or the engine falls flat on its face. Absolutely no power and sputtering. The engine never quits or stalls, but no power. I have replaced the plugs, checked the wires, and I do have spark at all three cylinders under a crank test. The plugs all look clean and dry. I changed the fuel filter, a few fuel lines, check the screens on the fuel pumps (2) and checked the coils per the service manual and all 3 have exact same readings. I'm at a loss here. The only other thing I can think of is that one or more of my coils is failing under load or the power pack is failing once it warms up.
Anyone have any ideas or similar issues?

Johnson 25 Outboard MFG. 10/1998
Model #J25RMECA
Serial # G04414368

 

[wifisher]

Re: 1998 25HP 3 cylinder Power/ Ignition issue?

When is the last time the carbs were rebuilt?

 

[JJGulley]

Re: 1998 25HP 3 cylinder Power/ Ignition issue?

Never, If you look into them they look like brand new. The fuel we get does not contain ethynol.

What about a overheating issue. The engine dosn't apprear to be running hot, the water pump appears to be pushing a good amount of water out of the p hole, maybe a stuck thermostat putting it into slow mode once it warms up?

 

[wifisher]

Re: 1998 25HP 3 cylinder Power/ Ignition issue?

Looking into a carb means nothing as you can't see the passages that matter. (the jets) Ethanol in the fuel does not cause the carb to go bad, nor does the lack of ethanol prevent fuel system problems. Carbs need to be rebuilt because of dirt and varnish that accumulates in them over the years. If it is overheating, the led should be lit. The best way to check if it is overheating is with an IR gun. If you verify that it is not overheating, and suspect that the sensor is bad, you can unplug it to bypass it.

 

[JJGulley]

Re: 1998 25HP 3 cylinder Power/ Ignition issue?

I don't thinks it's overheating, I'm just grasping at straws. I don't think it's the carbs. at this point because it runs great for the first 20 to 30 minutes. Once the engine is shut off and the heat is allowed to build up under the cowl then it starts to stumble. If it sits for a couple hours and cools then it runs great again. and every once in a while while it's stumbling it will take off and run great for 2-3 minutes like the ignition is failing and then correcting itself.

 

[wifisher]

Re: 1998 25HP 3 cylinder Power/ Ignition issue?

Have you ever run it with the cowl off? If the problem goes away with the cowl off, then you know that it is heat related and most likely an electrical component of some kind. Have you checked the timing on it yet? If the timing is off a little, maybe it shows itself more with a hot motor?

 

[JJGulley]

Re: 1998 25HP 3 cylinder Power/ Ignition issue?

That is one thing I have not tried

 

[hidef]

Re: 1998 25HP 3 cylinder Power/ Ignition issue?

Make sure all the electrical connections are tight and free of corrosion. A bad ground can send you into fits trying to figure out what is wrong. I don't believe you have a carb problem but it would benefit from having the carbs cleaned. You can also run it at night with the cowl off and see if you see any sparks jumping from the coils. Also have you done a spark test? If you haven't get a tester and set it for 7/16 of an inch. You should get a bright blue spark. You will want to test it after you get the engine hot since that is when you are having problems.

Also if you haven't removed the oil mixing system from your our outboard you should and start premixing 50:1. All of the OMS components have been discontinued and are all NLA items. Very hard to find and pricey.

 

[JJGulley]

Re: 1998 25HP 3 cylinder Power/ Ignition issue?

Thanks for all of the advice so far, do you know if this engine has a failsafe or slow mode that kicks in if an issue is present?

 

[hidef]

Re: 1998 25HP 3 cylinder Power/ Ignition issue?

Yes it does it will kick in if the engine is overheating. Check your thermostat or buy a complete kit from BRP it comes assembled and ready to go you just unscrew the old one and screw the new on in. That might be causing your issue. The other one is the temp sensor it is located between number 1 and number 2 cylinder. If that is going bad that could have an impact also. When was the last time the water pump was changed out she might be due. Take the cylinder and head temps with an IR thermometer and see what the temps are when she starts acting up.

You can a service manual from http://www.marineengine.com/parts/parts.php#manuals I highly recommend you spend the money. It has all the trouble shooting advice in it.

 

[JJGulley]

Re: 1998 25HP 3 cylinder Power/ Ignition issue?

Thanks, that looks to make more sense since it only appears to happen once the engine has reached full temp.

 

[hidef]

Re: 1998 25HP 3 cylinder Power/ Ignition issue?

You should also run premix 50:1 in your fuel tank until you are sure the OMS is working each spring but you really should get rid of it. They have high failure rate. The check valves in the mixing unit tend to fail allowing gas to go into the oil tank which dilutes the oil. Before you know it you are running 200:1 or more and your engine has died due to lack of lubrication. Remove the mixing chamber and oil tank then connect the fuel line that was connected to the output of the mixing chamber to the fuel filter.

 

[JJGulley]

Re: 1998 25HP 3 cylinder Power/ Ignition issue?

Ok you guys have convnced me, i'll get rid of the oil injection system.

 

[boobie]

Re: 1998 25HP 3 cylinder Power/ Ignition issue?

Check your replies on the "other boat forum".

 

[JJGulley]

Re: 1998 25HP 3 cylinder Power/ Ignition issue?

OK all, Here's the latest on the engine. Since my cottage is almost 9 hrs away I haven?t been able to get to camp until two weeks ago. I did hire one of the local certified marine mechanics to look at it in my absence. All he could find was a bent prop and he said the carb's were dirty and clogged. After spending $450 on a triple carb rebuild, when I arrived in camp the motor was just as bad if not worse. I found a place in town I could order a new power pack from, at the cost of another $450 and that took over a week to come in. Luckily I had access to a spare boat and motor. We'll as my original thought process confirmed, the power pack was the culprit the entire time. Unfortunately I had to pay full retail to get one since I was already in camp. While I had the engine down, I did remove the oil injection in its entirety, Installed a fresh water pump, new thermostat assembly and a new prop. The engine now runs as it did when new. I'm running the oil/fuel mix at 50:1 and it does appear to smoke a little more than it did with the injection system installed, but is running great at this time.

Thanks for all of your help

 

[hidef]

Re: 1998 25HP 3 cylinder Power/ Ignition issue?

Good to hear that it is now running properly again.

 

[watergecko]

Re: 1998 25HP 3 cylinder Power/ Ignition issue?

great to hear, dont worry too much about the smoke. 2 cycles will smoke-just means its getting proper lubrication.