2005 90HP Johnson missing

[rpaltazan]

I have a 2005 90HP Johnson J90PLSOA that has an intermittent miss after warming up. It appears to do better on cool mornings or right off the trailer, but seems to worsen after warming up. Also when I say intermittent, it has gotten to the point where it basically doesn't run WOT at all and sometimes kills at blastoff. It has been in the shop several times but they can't seem to duplicate the problem. I am guessing ignition rather than fuel base on the way it acts, but can't be sure. Short of just changing parts I am at a loss. Does anyone have tests that I can perform on the water for the power pack, coils, optic sensor ect. short of part swapping which would be rather expensive?

Thanks, Ray

 

[HighTrim]

Re: 2005 90HP Johnson missing

It does sound like a component of your ignition system is firing intermittently once warm. You could heat up the coils, PP, etc with a hair dryer then check the spark. It should jump the gap on the inline tester a good 7/16 of an inch with a bright blue ZAP!! Better yet do you have a partner and a inductive timing light to check for intermittent spark while under way?



If spark checks out you will need to look into fuel delivery.

 

[rpaltazan]

Re: 2005 90HP Johnson missing

I do have a timing light. I guess you are just checking to see if each cylinder is firing with the light while running, but there is no way to know if there is an intermittent miss fire with only a timing light. Is this correct?

Thanks, Ray

 

[khes142]

Re: 2005 90HP Johnson missing

Hi, I have an 02 Johnson carb 90hp V4. First step...you MUST buy an oem shop manual...about 75 bucks...essential!!! next you will need a digital fluke meter and an adapter to test peak volt readings to diagnose intermittent electrical problems.Very doable, but you need the right tools to do it. Good luck!!

 

[jtexas]

Re: 2005 90HP Johnson missing

see if this helps:

http://cdielectronics.com/portals/0/downloads/Troubleshooting Guide 2006.pdf