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The other day when attempting to power on to plane with my '85 Yamaha 90hp it seemed to be only running on 2 cylinders and was significantly lugging, when I added more power it died. Upon initially thinking I had a spark problem I began limping the boat back to the harbor and then after playing with the throttle the engine suddenly came to life and we cruised in easily. If I pulled out on the control arm and reved the motor in neutral the engine ran smoothly, then after I engaged it in gear again I would get the lugging and eventual dying of the motor.

Is there a safe mode that is engaging somehow that is rooted in the control box? Any ideas of where to start trouble shooting? Thanks for any ideas in advance.

Dylan Rose

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Dylan,

I have a 90 HP as well. There is a safe mode but the CDI initiates that function, not the throttle lever. It engages for two reasons, low oil, and over heat. Did this happen after the engine ran a while? Does your buzzer-horn go off when this happens? I would check all the usual suspects, fuel delivery being main one. All lines for leaks in the engine and from the tank, the filter on the engine and water separator for water. When running does the bulb stay firm? I would also do a compression check....

Also you did not mention if you recently purchased this outboard. Has it run fine all along?

good luck

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Thanks for the response. The saftey horn is not sounding although I did have a problem with it continually going off until I changed the impeller last fall. The motor is acting similarly to when the horn would go off and the safe mode would engage. I'm now getting good water flow discharge and I have plenty of oil.

The strange part is the problem started after I had been trolling around with the kicker for probably two hours. We went to move general locations, I fired up the big motor and that's when it occured. Upon limping back to port with the big motor i began fooing with the throtle lever, pulling it in and out of gear, and bingo all of a sudden she came to life and we were off on running. After I got close to the marina I pulled OUT on the lever to engage neutral, reved it (it sounded good) then went back to put it in gear and the problem was back. Very strange indeed. This leads me to believe it is not a fuel, spark, or compression issue, but something with the control lever itself. Is this a wrong assumption?

Dylan

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Dylan,

I think you may have the wrong assumption.

When the boat is not in gear, the engine will usually rev up just fine even if there is a minor problem with the engine.

Problems usually only show up when they are IN gear.

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Okay, went out and confirmed good fuel flow to the carbs via cranking the motor and pumping fuel. Confirmed spark with plugs against the block and have looked over the fuses. I've inspected the fuel filter and it appears to be in good shape and I did not find any water.

In the throttle box, is there a switch that could be malfunctioning or is that mechanism purely analog and mechanical in nature? Thanks, and sorry for sounding desperate but the salmon are in and I'm dry docked!

Dylan

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Dylan,

There is nothing in the control box other than the safety neutral switch.
This switch should not allow you to start the engine if it is NOT in neutral.

Other than that..... Nothing....

It seems you have some kind of electronic problem in the engine circuitry or a fuel problem.

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Joe,

Thanks for the input. This link in continuous wave sounds very much like what I am experiencing, if you're interested.

http://continuouswave.com/ubb/Forum3/HTML/011974.html

I am going to think oil level sensor for now and see what happens, as replacing the CDI does not sound like fun cost wise. Thanks.

Dylan

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The oil sensor will be tricky to test. If you remove it you will have a mess if you tank is filled above the sensor (about half). And let me tell you it is not easy to remove... Like a cork in wine bottle. You may be able to carefully remove the tank and flip it upside down, not easy either because of the hoses. I do not think you will be able to switch the wires because the connectors are male female and it work on resistance, ohms.

What I do from time to time to test it is to let it run low and tilt up the engine. This will activate the alarm if it really low. I do not like letting it run in the red zone because it is almost like it is completely out of oil when the alarm will go off. Do your indicators work properly, Green and yellow?

Good luck

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Hmmm... Lights on the console seem to indicate correct oil level. Does this mean the sensor is operating correctly? Is there any way to run a diagnostic on the CDI?

Dylan

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Probably not a control lever problem. Probably not electrical or computer problem either. Might be something as simple as a bad O-ring on the fuel line connection to the motor letting a little air into your fuel. Maybe a fuel problem in the form of stale fuel, ethanol-related, or just small amount of condensed water. You don't say what model of boat you are running... Are you working with portable tanks? I've heard some people say running the fuel tanks dry can foul the motor as too much oil gets sent into the motor.

I once had a very similar sounding problem with my 70HP 2000 Johnson. Long story short I replaced the fuel line, primer, and connectors from my tank to my motor and no more problem...

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I agree the problem has nothing to do with the controls. The symptoms sound exactly like a fuel starvation problem.

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okay, I'll replace the fuel line connector to the motor as it's the last of the old components from the tank to the motor. A fuel issue would be certainly better than a CDI problem. Also, I've never run this motor dry of gas since I've had it.

Dylan

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Yesterday I installed a new yamaha 6 gallon tank and full line so as to be sure my connection from the tank all of the way to the motor are good. Put the boat in the water and upon advancing the throttle slowly the motor lugged and quit several times. After the motor died the second time I advanced the throttle forward quickly giving it plenty of gas and the motor came alive and ran beautifully up to plane. Throughout the course of the evening the problem seemed to get better. I do notice that it takes a few seconds for the position of the throttle control seemingly to register in the motor. Is there an adjustment that can be made? Do I have a clog somewhere from potentially old gas? Thanks.

Dylan