98 johnson-90horse firing on 3 cyl. out of 4

[Janelle]

I have a 1998 johnson 90 hp 4 cyl. it is only firing on 3 cyl. the coil is good, I changed it with another, the power pack is brand new, i replaced it. Still no spark in 1 cyl. any suggestions, I would really appriciate it.I pulled the fly wheel it does not look like anything is loose, I dont know what the trigger r magnets look like, I was told by someone to replace the timing base. Any suggestions other than what has been done?<br /><br /> thanks,<br /> Janelle

 

[Beernutz]

Re: 98 johnson-90horse firing on 3 cyl. out of 4

Is this a 60 degree motor with optical ignition? If so, remove the plastic flywheel cover. You'll see the numbers 1 thru 4 on the top of the timing wheel. Hook your timing light to each of the plug wires in succession, while the motor is running. Be careful not to point the light at the optical pickup sensor. As you progress thru the plug wires, the number corresponding to each cylinder should be stopped by the timing light at or near the pointer. If they all show up on schedule, the problem is not with your ignition.<br /><br />Which cylinder is not firing? Is there moisture on the electrodes of that plug? If so & it's #4, it could be a lower main crank seal failure.

 

[Fouled Plug]

Re: 98 johnson-90horse firing on 3 cyl. out of 4

Start with the basics. Try a new plug in the non-firing cylinder and eliminate a bum spark plug.