weak ignition system

[gregs]

can anyone out there in outbourd world verify what repair shop told me today. they said that 74 through 76 evinrudes have a very veak ignition system. i took it to them thinking something major was wrong. all they did was install an NGK B7HS plug. after i paid them close to $50.00 they told me now we cant tell you that you wont foul them out also. this is why i took it to them. it kept fouling plugs. its a 9.9

 

[seahorse5]

Re: weak ignition system

That ignition system is "weaker" than electronic CD ignition, but is stronger than regular point and condensor systems.<br /><br />The correct plug for your motor is Champion UL81J, it has an auxiliary gap internally. Make sure the thermostat is warming the motor up to around 140 degrees to prevent fouling.<br /><br />Years back there was a service bulletin about changing out the driver coil under the flywheel.

 

[hondon]

Re: weak ignition system

I don't know about weak,but these engines did have points rather than CD ignition.That can mean that if you are trolling around really slow the charge coils are barely generating enough current to fire the plugs. Also what is the condition of your point sets ? How long have you owned this motor and have you changed them?How are you mixing your fuel and with what kind of oil?Are you propped right or are you making this engine do more work than it was made to do?

 

[Boatist]

Re: weak ignition system

You are not alone. Right now at least three people fighting same thing on Same motor. Mine is a 15 HP 1974. Mine is hard to start in early morning but once warmed up runs fine until foul plugs. My motor would foul two sets of plugs a day trolling for salmon. I found thermostat stuck open so I changed it. After that warms up much better and plugs last about 1 day. Went to two heat range hotter plugs that also help just a little. On my motor have changed both points and condenser timed it but had no effect on plug fouling. In later years they did redesign the head for this problem but my motor was fine 20 years before this problem started. Last weekend pulled carb and checked but all jets open. Did find float set too high allowing to high a fuel level but only by a little bit. Did compression check on my motor cold tonight and top is 120 bottom 115. I will let you know if find problem please do same if you find a fix. Only difference in our motors is the carb is biger on the 15.

 

[seahorse5]

Re: weak ignition system

The 9.9-15 came out in 1974 and right away had a recall for low speed problems. Upgraded motors got a redesigned cylinder head on the 15 and new carbs for both hp motors. There were several spark plug changes. About a year later they redesigned the driver coil and sent out a bulletin about that. When they went to CD ignition, plug fouling was almost non-existent.<br /><br />Now your motors are up to 28 years old, parts are worn,linkage is loose, and age, use, and corrosion takes its toll. Grab the magneto plate under the flywheel, does it "rattle" or move around on its pivot? Chances are it does. There is a repair kit available but its pretty expensive for an older motor.<br /><br />Decarbon the motor, set the points slightly closer to allow for the "slop" in the magneto plate. Change out the driver coil under the flywheel and make sure there are no cracks or arcs in the external coils. Use the UL81 plug, check the thermostat, rebuilt the carb, and synchronize the linkage according to the manual. Your motor will then run the best it can. On the 15's, the engine must prop out close to 5500-6000 for it to troll well. The 9.9 is not as fussy. There is more than just a carb difference between the motors.

 

[Boatist]

Re: weak ignition system

Seahorse thanks for reply. I had my motor since new and never got any recall form JOHNSON. It is a 1975 and ran perfect for 20 years or more. In fact only changed plugs 3 times in first 20 years and even then not for any trouble. In fact I really did not have any trouble until TCW-3 oil came out. I did work on my motor today and found a major problem. I wish I had seen you suggestions first. The top plug has a very weak Spark caused by the ingition coil. Easy to diagnoise as input wires are on plugs so swapped plugs on input and spark plug wires on output and weak spark moved to bottom cyl. I also checked the magneto plate and it seams very good. With points setting on lobe and pushing it all around point gap changes less than .001. The points gap are set to .020 and off lobe have .030 gap off lobe. I have checked linkage syncronizeing many times and it is good and timing is perfect. All I have been able to read on difference between 9.9 and 15 is Bigger carb. 9.9 has a .625 throat and 15 has a .875 throat and bigger jets. In 1987 they did tune exhaust to raise prop shaft HP up to 15HP. I am using a champ L90C plug which is two heat ranges higher but my book called for a L7J plug. I will try the decarb thing as I have never done that. Is that something you spray in carb or put in gas or both. I have check engine temp and thermostate and they are fine. My plugs foul but if I take them to the to the tourch and burn oil out they are fine again. Thank for all your help. I am hoping Evinrude starts making 15 HP 4 stroke again soon.

 

[seahorse5]

Re: weak ignition system

Only the early 74's had the recall.<br /><br />See your dealer and get a can of #771297 Engine Tuner (carbon cleaner) and follow the instructions. Do it 2 times, 1/2 can each time.<br /><br />Install the factory recommended Ul81J plugs.<br /><br />If you can hold your fingers on top of the cylinderhead for more than 2 seconds, your motor is running too cold, and needs a thermostat.

 

[gregs]

Re: weak ignition system

ok seahorse sounds like your pretty knowledgeable on these evinrudes. since this is the case i've got some more questions<br /><br />1. the prop on my 76 evinrude would probably do but its got quiet a few dings. if i wanted to replace. how would i know which one to ask for? i could take the old one i guess. but i see all of these pitch #s what do they really mean? <br /><br />2. were exactly is the thermostat on the 76 evinrude? mine probably is bad if your saying it should be pretty warm. i had felt my head thinking it was good for it to be cool to the touch. maybe this is why im fouling these plugs. i took it out today and it ran better with the ngk plugs they installed. but i could tell it still was'nt right. i'm going to try this champion your talking about.<br /> <br />3. i'm not sure i have my throttle adjusted right. now i can put it in slow position an it will idle just fine. i took the manuals back to the library so i dont know the names of all the gadjets. but theres an screw with a screw driver slot in it. it may be the coils but if i take one plug wire off it will run a few seconds and eventually die. but so will the other one. but if i idle it up a little its ok.

 

[Boatist]

Re: weak ignition system

Seahorse Thanks I will try that engine tuner, I am not sure about plug, that plug would be one range colder than what engine came with and what my manual says. It call for a L7J which crosses to a L82C plug I am running is two heat ranges hotter a L90C or 896. I only use my motor for trolling or in ocean for backing when winds get up over twenty. The thermostat is fine on my motor have checke it several times in pan and it opens at 150 degree. Also held down a thermoater to block and it reads 140 plus. Can touch block but not for long. I have not been able to find a ingnition coil yet so may have to order one. Thank again.

 

[Boatist]

Re: weak ignition system

Geegs Standard prop that motor came with is a 3 blade 9 1/2 dia by 10 pitch Part number 386118. Good for a 10 to 14 foot light aluminum boat. I also used that prop on my 20 foot boat for many years and it work fine. If it not too bad I would just file the burr off. 3 blade 9 3/8 by 9 stainless steel is p/n number 389892 and a 4 blade 10 dia by 9 pitch high thrust prop is part number 176266 and has a 60 % higher rear thrust.<br /> The thermostat is under the back most cover near the cover latch. Some of the bolts hold spark plug wires, If you pull it may need a new gasket. Thermostat should open at 145 degrees.

 

[Boatist]

Re: weak ignition system

 

[seahorse5]

Re: weak ignition system

If you use the motor as a kicker for trolling, use the "sailboat" prop for more thrust and better running.<br /><br />It is sometimes easier to just pull the cylinder head and then the rear cover to replace the thermostat. If used in saltwater, you will be cleaning corrosion out from the cylinders and passageways.<br /><br />Get the manuals or copy the section on carbs and linkage adjustments. They are critical for drivability.

 

[fireman 757]

Re: weak ignition system

Does this apply to 1976 35 horse evinrudes too or just the 9.9 and 15's. I'm fighting the same thing on this engine.

 

[Boatist]

Re: weak ignition system

I put new ingition coil on and have good spark on both clyinder now. Starts with a half pull now. <br />One thing I did notice is each cylinder runs best with a different low speed mixture. There is one point where each runs pretty good so that is where I set low speed mix and then recentered the knob. <br />What would cause each cylinder to run better with a different mix of lean or rich?? The compression on the top cylinder is 120 and the bottom is 115 is that enough to cause problem??? Check compression with engine cold. Could it be a reed that is the cause??? I pulled each spark plug wire and adjusted mixture but each cylinder runs best at a different point.<br /><br />I also got the engine tuner but looks like I need a litle time to do the decarb thing as it says spray in and wait 3 to 16 hours then start and run at least 20 minutes so will have to wait for weekend.

 

[Boatist]

Re: weak ignition system

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