1976 evinrude 9.9 eating plugs

[jeremy5780]

I have a 1976 evinrude 9.9 modle 10624H. It eats up spark plugs like crazy. If I put in a new set of plugs (marine champion Ql77jc4) motor will run great for a few hours 2-4. Then motor will feel as if its loosing power and when put in nuteral and reved up it is slow to get to full throttle as if there is a delay. But when u pull the plugs out and replace them it's like a new motor. I have tried cleaning the plugs but nothing, it's like they are destroyed and cannot be used again. When I pull the plugs out they are not wet or oily as if they where getting fouled. they look like a normal plug with a little black carbon on them. Any thoughts???????????????? I have also tried diffrent brand plugs with the same result.

[levi_tsk]

you sure your running the correct plug ?? i believe that those are suppose to run a champion j4c or if you do ALOT of trolling champion j6c ?

[Monte1961]

SPARK PLUG, CHAMPION L-7J is what spects call for that motor i do believe? Post back and let us know.

[Rick.]

Once your sure you are using the right plug do a spark test to see if your spark will jump a 1/4 inch. Spark should be blue/white and snappy. If you have week spark perhaps new plugs compensate for a little while and then not. Best of luck and keep us posted. Rick.

[kbait]

You're using plugs for a CD ignition motor ('77+). You have a low tension point ignition setup. Get the right plugs and you'll fare well!

[levi_tsk]

iboats store says he needed UL81C's not sure if thats right but the champion website said the same thing so?

[ezmobee]

I know the iboats store specs incorrect plugs for my motor as well.......

[OptsyEagle]

You are using the wrong plug and the ones you are using will foul within a few hours, everytime. Fouled plugs cannot be cleaned very well. Also, those motors hate champion plugs. Use NGK B7HS and if you like to troll a lot use NGK B6HS. Any other champion plugs on that motor will cause you problems.

I have a 1975 9.9Hp and a 1976 15Hp and both will not tolerate Champion plugs. I use Champions in other motors with no problem, but not the series of motor you have.

When you are done, you should do a decarb. If carbon is gettng on your plugs (that is why plugs fouls) you can be sure it is getting in your cylinders and piston rings.

[OptsyEagle]

By the way. Even when you do use the NGK plugs in your motor, you should always keep a spare set in the boat and these plugs should be changed every year, unless the motor has very little use. That series of motor tends to foul plugs. If you use NGK you can probably get 1.5 to 3 years out of a plug as opposed to the correct Champions (you were not even using the correct Champion) of less then one season.

I keep a set of plugs and a socket wrench in the boat. I have never needed them, since I switched to NGKs but it makes me feel better knowing their with me. Since the NGKs last so much longer, usually a fouling just means one cylinder going and the other working enough to get you home. With the plugs you are using, they will, many times ,both foul within minutes of each other.

Now you are rowing.

[jeremy5780]

what do these NGK's need to be gapped at?

[levi_tsk]

most probably whatever the stock gap was...

[OptsyEagle]

0.030" gap.

[OptsyEagle]

A few other things just for your thought process. A spark plug with foul if you are running too rich or you are running too cold. The carbon comes from the improper burning of the fuel in the combustion chamber.

Since the plugs you were using are too cold for that motor, I will assume that is your problem. To be on the safe side I would also want to make sure my motor's thermostat has not failed open and my carb was adjusted for the proper enrichment of fuel.

On your motor the T-stat check is easy. After the motor has sat for 5 minutes, start it up. Check the exhaust hole for a very light spray that is almost unnoticeable by eye. In about 10 to 15 seconds that spray should increase to the point where it is easy to see. If this is the case your T-stat is fine. On your motor the spray out the exhaust is severely restricted until the t-stat opens (in about 10 to 15 seconds). If the spray is significant, immediately after starting, then it is possible your T-stat is stuck open. This will lead to a motor running too cool and reduce the life of your plugs (and your motor).

As for the carb. When you next run it, set it properly with this procedure for a carb with only a slow speed adjust.

http://forums.iboats.com/engine-frequently-asked-questions-faq/carb-needle-adjustments-asorted-carb-variations-joe-reeves-167352.html

[Faztbullet]

UL81 c is correct plug for this engine.....
9.5 1964 - 1973 J4C .030
9.9 1974 - 1976 UL81C .030
9.9 1977 - 1994 QL77JC4 or QL82C .030

[OptsyEagle]

UL81 c is correct plug for this engine.....
9.5 1964 - 1973 J4C .030
9.9 1974 - 1976 UL81C .030
9.9 1977 - 1994 QL77JC4 or QL82C .030

That is correct and I would bet on the 1964 to 1973 and every motor after 1976, those plugs would be the ones to use. On the 1974 to 1976 9.9/15Hp series, the UL81Cs (OMCs recommended plug)will not work as well as the NGK B7HS. If you follow the history of the spark plug recommendations out of Outboard Marine for this series of motors, you can't help but come away with the feeling that they knew the UL81Cs don't work very well. Since no other Champion plugs were any better and they had some serious resistance to recommending any other brands, the last word is where it is. Once they developed the CDI system in 1977 the fouling problem went away so I suspect they have stopped trying to figure out what to do about it.

That is my thoughts on the matter. Good luck in whatever plugs you use.