evinrude 9.9 1979 poor idle,loud exhaust,less power

[Rick.]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

Unlikely but it could be. I had a chunk of plastic stuck in mine. The plastic was a 1/4 of the slow speed needle dial. Another fellow found a tie wrap chunk in his so it does happen. I think it is worth checking at this point. Seems like you've tried everything else. Rick.

 

[AlTn]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

I'm in agreement with Rick as all the ignition system can do is produce the 7/16" spark at the right time which is what you have observed. In the past, I've held a rag over the sparkplug holes and pulled the motor through just to be sure fuel, in some quanity, was reaching the cylinder. Advise ground the plugs, or plugwires, so no spark is present while doing this.
In the future you can avoid cutting those wires from the pp to the coils by pushing the pins out of the amphenol plug and swapping the position of each in the plug itself. I've used the head of a nail to do this and it worked well.
Post updates as this thread may very well help someone in the future.

 

[Hughjohnson]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

Thankyou both. AlTn i was wrong when I said that swapping the coils tested both sides of the PP. It doesn't because the pp signal(pulse ) for the bottom cyl still goes to the bottom cyl even if it goes thru a different coil and HT lead.Now I know I get a 7/16 spark but is the timing right ? I do not know so I should check that. But is it physically possible for the timing to be wrong for one cyl and right for the other.?? I'll will check ignition timing next when I figure out how to do that.
One more question if you put a rag in the plug hole should it get wet with oil gas mix or just smell. I will do this test because I may not be getting enough gas. I only know that the plug is wet with oily gas after a short run.
thanks again. Hugh

 

[AlTn]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

timing is set with the position of the crankshaft key and flywheel...no adjustment...so, if it's right on one it's right on the other. At the amphenol plug coming from the pp to the coils: A. is yellow/black and is the kill circuit wire coming from the shorting switch B. is orange/blue from the pp and comes out of the plug as orange going to the #1 cylinder coil C. is Orange from the powerpack and remains orange to the #2 cylinder coil. I'd suggest you make sure each wire into and out of this plug are in the correct position now. I say this only because if they can be switched, I've probably switched them at one time or another, and no it will not start with them reversed.

I just push a little bit of rag into the sparkplug hole with my index finger and pull the motor through 3 or 4 times. You should have an observable amount of moisture from each cylinder. Obviously you don't want to "stuff" the rag into the cylinder any further than a sparkplug would extend into it.

If you have the wires in the proper connections through the plug and you are getting a 7/16" air gap jump from each, there's nothing else to be concerned with ignitionwise. No timing to adjust.

 

[Hughjohnson]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

thank you AlTn. I spent an hour or more reading how the CD ignition works and as you say the timing cannot be adjusted and there is only one sensor coil for both cyls. So yesterday I did the rag test but I ran the engine on the top cyl with the plug out on the bottom cyl. I pushed the rag (terry towel )on the end of a screwdriver into the plug hole ( quite a pressure isn't there ! ). Took the rag out and it was not wet. I put my finger towards the hole and it was immediately covered in oily/gas mix,as is the plug whenever I take it out. So we are getting gas. Next item was to look at the reed valves.One test for a faulty stuck open reed valve, according to my manual, is to hold a stiff piece of paper over the carburetor intake. If the reed valve is stuck open you get blow back and the paper will get gas on it. I did the test and it stayed dry and there was no indication of blow back. Now I am stuck again but while I was there I checked the compression again and it was 110psi which is OK I did not check the good cyl which was 120 before the taking the engine out. I really do not know what to do next. I am curious to look at the reed valves but I do not want to take the engine out again. do you think it possible to get at them with the engine still in place??.
Merry Christmas to you all, Hugh

 

[OptsyEagle]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

Hugh. I can't remember but did you eventually remove the powerhead and if so did you replace the lower crankcase seal?

 

[AlTn]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

Hugh, if you haven't done so already go to Leeroy Wisner's website..Leeroy's Ramblings..specifically to Info and Normal repairs for 1974-1992 9.9-15 hp. ...scroll down to a page labeled 22OB < left hand column>..scroll to removing the intake manifold he discusses this....a wealth of information and experience is provided by him covering the 9.9-15 hp. series...his member name is The Machinist

 

[Hughjohnson]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

Yes engine was removed and new seal O ring put on and the main seal which was replaced in 2010 was in excellent condition. Cyl head gasket also replaced. I will certainly check out Leeroy's ramblings much of which I have read and thoroughly enjoyed.We have not heard from the machinist for a while Hope he is well. he is the same age as me only he is way more experienced.

 

[Hughjohnson]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

OK I took the engine out again and took off the carb and reed valve cover and there was the problem. a part (about a quarter ) of one of the 2 reeds of the lower cylinder was broken right off. As you know it is just a piece of thin steel so why a part of it should fracture off like that is really surprising to me.Should I be taking apart the crankcase to find the missing piece ??
Anyway we have solved the problem and learnt the following. If a cylinder is not firing and its piston and head are incredibly clean and there is no water on the plug it could be a broken reed valve. the 2nd lesson is that the test for a broken or stuck open or jammed reed valve does not work very well on a 2 cyl engine. ( that test being the stiff paper at the carb inlet with the engine running where it was supposed to show blow back by vibrating and getting covered with gasoline and oil ). the reason the test does not work is perhaps that on a 2 cyl engine one crankcase is sucking in just as the other is blowing back and hence stopping the blow back from reaching the carb.
hope this makes sense. Thank you all for your help and patience and a happy new year.Hugh

 

[jmendoza]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

That louder exhaust was the increased intake roar from the crankcase. To diagnose a bad reed, a case leakdown test will not work, but I have mentioned on this forum before about listening for the reeds to make a "honking" sound as each piston is on it's upstroke. This is done with the spark plugs removed, but plugged in and grounded, and slowly turning the flywheel by hand. One cylinder(the one on the upstroke) will honk, while the other one makes a "thoo-pah" sound as it vents it's crankcase on the down stroke. This is something I always listen for before putting the head back on and after any carb or manifold service or overhaul on a 2-stroke. Crankcase compression, or lack of it, is a often overlooked criteria that is just as important as top end compression, in fact, as you just found out, it's more important!