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1989 115 Ignition problems

guido2

guido2

Regular Contributor
"I am having troubles now for

"I am having troubles now for 3rd year with this motor. At slower cruising RPM, under 4500, no misfire. When pushing harder seems loss of spark on 2 lower cyls. Not sure if one or both cyls loose spark but they seem cooler to touch after symptoms. If you back down and slowly bring up speed, sometimes will get back going with intermittent firing on all cyls. After cooling down and restart will be fine again until you try to push too hard again and engine reaches full operating temp. Boat is beautiful and never abused, used only for transport and freighting into remote Ontario. Is there an ignition problem that affects this vintage Merc? Doesn't matter what you do with spark plugs, but throttle position seems critical to keep going once motor starts to act up. Yesterday got in trouble trying to stay ahead of a thunderstorm so its time to pursue this repair. Thanx for any advice as I am a marine mechanic as well but more familiar with OMC. Eng serial #OC206055 with Comp Prop 4 x 12.8 x 17. Plugs QL78YC which all look dark brown. If motor persists on acting up I always reduce power until will run again on all 4 cylinders. I think we are going to need a sharp tech on this one. I have a DVA meter of course but not a service manual that covers this motor. Thanx for any help. Tim"
 
"Hello out there.......doesn&#

"Hello out there.......doesn't anyone want to touch this question? Maybe a Merc pro has seen this before. Thanx, Tim"
 
"you can get the specs from th

"you can get the specs from the cdi site here, troubleshooting and dva
http://cdielectronics.com/Downloads/tabid/55/language/en-US/Default.aspx its a safe download

I would put a timing light on each plug wire and check for consistant spark when it messes up. Sounds like a heat related problem and will be hard to find unless you remove the flywheel, look, and maybe take a hair dryer and check everything when hot. Good luck"
 
"Thanx JB. With component temp

"Thanx JB. With component temp an issue it reminds me of a Belgium made Merc I once repaired that ran only at certain temps. Warm it had spark, cool.....no spark. Replaced trigger, that was it. This was the little single cyl however. Could the trigger on the 4 cyl affect this multi cyl motor with partial spark loss? Or would it more likely be in the stator or control module? I might pump my well dry trying to figure out this one. I could never load the motor enough to develope the symptoms. Any more ideas? Thanx Tim"
 
"The most common problem like

"The most common problem like this on a 4 cylinder like this is the stator.This ignition stator is set up like two 2 cylinder ignition systems.The red wire and blue wire runs 2 cylinders and red/white and blue/white run the other two.The blue wires are for low speed,to about 2000 rpm and the red wires are for high speed,above 2000 rpm.My guess is that one of the high speed sections is bad."
 
"Thanx Paul, welcome to the si

"Thanx Paul, welcome to the site. What a great resource. I recognise some experience here. I like to help out when I can. I have been OMC trained and professionally repairing in every field of mechanics and welding for 40 plus years.
So what you are saying is that perhaps if I heat the stator to full operating temp......hair dryer or heat gun......I would see the impedence on low RPM side of cyls 3 and 4, exceed listed parameters?"
 
"If you go to CDI electronics

"If you go to CDI electronics you can download the test procedure to check the stator.You will be able to test both high and low speed sides of the stator with an ohm meter.All the specs will be there,as well as the procedure."
 
"Thanks, maybe the impedence i

"Thanks, maybe the impedence is already outside parameters as testing allows for some slack."
 
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