2002 johnson 50hp intermittent rough running lacking power and check engine light

[OttawaPhil]

I have a 2002 J50pl4st fuel injected 4 stroke.
has 650 hours on it.
oil changed and plugs and fuel filter about 2 months ago.
I've never had a problem before but today it has started to intermittently misfire and lack power and even had check engine light up solid plus the buzzer.
I started it this morning and idle was very rough like misfiring. Let it warm up for a while hoping that would fix it but it did not. Tried to go wide open throttle to see if that would help and it would not go over 10 miles per hour. After a couple minutes of that the check engine light came on. Stopped and looked under the cover and did not see any signs of visual problems. External fuel hoses and such look good. Also noticed the voltage in gauge was at 14.1v not sure if related. Don't remember it being that high before.
over the next few hours I started and stopped it about 10 times to move us around while we fished. It ran perfectly about half the time the other half the time it would run rough with no power and the check engine light on.
What else should I check? Is there a way to read codes on the check engine light? Are there known problems that cause this sort of thing? Thank you very much for your help.

 

[OttawaPhil]

What should I do to diagnose this?

 

[OttawaPhil]

I have time to go back to the water now. Will be leaving in a few minutes. Back in the water in an hour or so. Can anyone tell me how to read the check engine codes? Or anything that I should check?

 

[jakedaawg]

Water in fuel...

 

[OttawaPhil]

I pulled the fuel filter and drained it there was no water in it whatsoever. The fuel tank was even out of the boat a few months ago and drained. Not a old fuel or water in fuel issue.went out again yesterday and it squealed nonstop every time I started it it is now showing error code 13 as soon as you display codes there is one flash than three flashes which repeats. I have not been able to find code 13. Does anyone know what code 13 is?
thanks

 

[racerone]

I have a 4 stroke manual for JOHNZUKI 50 hp.-----Perhaps not your year.--------787061-----No code 13 on the list.

 

[OttawaPhil]

I wonder if it could mean 31?
have the code for that?

 

[racerone]

31 is for IAC valve / bypass air adjustment.

 

[OttawaPhil]

I wonder if iac would cause rough running? Dan the iac be tested with meter or something?

 

[jakedaawg]

It will stall under deceleration usually with a bad iac or dirty iac. Factory set.

 

[OttawaPhil]

It has never stalled. Just the symptoms I listed above.
Any ideas of what to check or test?
Supposed to be out duck hunting in the boat, not in garage working on it 8-(

 

[jakedaawg]

Low battery voltage will cause check engine lamp and 10 second warning buzzer.

 

[jakedaawg]

If you have a weak battery and start the motor, in addition to a jack plate or pump or trimming motor, the battery voltage could drop below 9 volts causing this to happen. Have battery load tested. Minimum 650 mca battery. Nuts and a wrench, NOT wing nuts. Clean scraped battery terminals at both ends, block and battery.

 

[OttawaPhil]

I have it in my driveway connected to the hose and muffs. It is running rough in my driveway. I have confirmed it is indeed code 31 which is for the idle air controller. I have just tried to adjust the idle air controller. When I pull that hose off and cover the end of it from the airbox. Then the motor would stall. Adjusted the screw on the IAC until got the proper RPM with it covered then put it back together. No change for how it runs.

I also have been able to see that it is the top cylinder that is misfiring. I removed the lead on the top cylinder and it does not make a difference. So I have just swapped spark plug and ignition coil from the top cylinder with the bottom cylinder and started it again. Still the top cylinder is the one misfiring. What would cause the top cylinder to misfire other than the ignition coil or spark plug which were both swap to the bottom?

Any ideas to check? Have it out for next few hours time to work on it .

Thanks a lot for your help!

 

[OttawaPhil]

Checked battery both less than a year old 12.5 volts off and 14.0 running

 

[OttawaPhil]

Oh and I cleaned them and put real nuts on when I replaced them. In excellent condition. Appreciate the idea tho8gh very much

 

[jakedaawg]

I mis spoke, stall under deceleration with a bad ctp or dirty bypass. Try cleaning iac valve and throttle body including idle air bypass passage. That would be free.

 

[jakedaawg]

Needs a load test for battery, voltage test tells nothing. Anyways, low battery voltage is what illuminates the check engine lamp on that motor. So, if battery is good then it's the ecm thinking its low for some reason or another...

 

[OttawaPhil]

Would Dirty iac or throttle body cause the top cylinder not to fire?
even when i swapped the plug and coil with the bottom one it's still not firing on the top one.

thanks

 

[jakedaawg]

No.