Type II CD Ignition 1979 15 hp 'rude

[michiganmarty]

Can anyone tell me what to look for? My engine has a definite ignition miss. Sounds and feels like the miss is every-other-revolution, but I have no way prove it. It is most evident at an idle, but can be heard, seen, and felt at all engine rpm. <br /><br />The engine is fresh, new everything except ignition components. No crankcase leaks. The engine runs very strong.

 

[JB]

Re: Type II CD Ignition 1979 15 hp 'rude

Hi, Marty.<br /><br />There is another thing that can cause "every other rev" running. We old timers call it "four cycling" and it is a symptom of too rich fuel/air mixture. Could this be your problem? <br /><br />Try shutting off the fuel flow when running under load. Does the engine suddenly smooth out and develop full power before starving and dying? If so, you are four cycling from too much fuel. Overhaul your carb, with special attention to the float needle and seat and the installation of jets.<br /><br />It is also possible that your engine is running on one cylinder, though you don't complain of lack of power that this would cause.<br /><br />Try disconnecting each spark plug, one at a time, and try to start it. Starts on one cylinder but not the other? You have a dead cylinder. could be lack of compression, lack of spark, air leakage into crankcase or bad reed valves.<br /><br />Let us know what you find.

 

[michiganmarty]

Re: Type II CD Ignition 1979 15 hp 'rude

Thanks for the reply!<br /><br />This old timer understands exactly what you mean by 4 cycling...but that is not it. Carb is all rebuilt too, I knew it wasn't the carb because the engine does it through ALL the fuel circuits, lowest idle through top RPM. It would have to be the wrong carb to be pouring too much fuel at every throttle plate setting. <br /><br />Additionally, it would load up in a hurry and stall if a rich mixture were the culprit. I ran it around the lake yesterday at an idle for 1/2 hour with-out any more than the usual so-called miss.<br /><br />As far as shutting off the fuel, I did exactly that by purposely running two fuel tanks dry yesterday. (break-in, you know)<br /><br />This engine displayed the same miss before and after the rebuild. Again, the only thing not fresh is the ignition system. <br /><br />I am going to check the system with a .500" gap tonight to see if one coil is weak. Then I'll work back from there.<br /><br />I was just hoping someone knew of a system weakness this model had that I could check quickly.

 

[clanton]

Re: Type II CD Ignition 1979 15 hp 'rude

Most probley the powerpack, coils, or sparkplugs wires. A good spark would indicate a good charge coil.There is only timing one sensor, so if engine runs, sensor should be good. The sensor fires on the north,and south end of the magnet in the flywheel.

 

[michiganmarty]

Re: Type II CD Ignition 1979 15 hp 'rude

Ok, here is the skinny:<br /><br />I placed a 1/2" gap plug on each wire and cranked it over - both put out a hot blue snapping spark at what seemed to be 180 degrees out of phase.<br />Would the module contribute to the so-called miss even though there is plenty of spark?

 

[michiganmarty]

Re: Type II CD Ignition 1979 15 hp 'rude

I assume the "powerpack" is the black module which is bolted to the right side of the motor, just behind the exhaust coolant cover (close to the cylinder head)?

 

[Xcusme]

Re: Type II CD Ignition 1979 15 hp 'rude

Marty,<br />Yup, that's the powerpack.... <br />I have the same year,make,model...<br />BTW, what are the compression figures for both cylinders??

 

[michiganmarty]

Re: Type II CD Ignition 1979 15 hp 'rude

Xcusme,<br /><br />Sorry for the delay in answering your question...<br /><br />The compression on both cylinders are 100+. This motor is not completely broke in yet. It is 'fresh'.<br /><br />Let me get this straight, if I get a good hot spark on both plugs, about the only thing that could be bad is the powerpak?

 

[Xcusme]

Re: Type II CD Ignition 1979 15 hp 'rude

Did you replace both upper and lower crank shaft seals with the rebuild?? Could you have a leaking fuel pump diaphram sucking extra fuel into the top cylinder??<br /><br />You say the ignition system produces a hot spark to both plugs so lets put that issue on the side for a second. The carb is common to both cylinders but the reeds are not. Did you do the dollar bill test to look for 'back puffing' of the carb?? Do both plugs look the same??<br /><br />Just throwing out some ideas here....

 

[michiganmarty]

Re: Type II CD Ignition 1979 15 hp 'rude

Xcusme,<br />Please pardon my lateness in replying to your response, I really do appreciate the help offered by you or anyone else in this forum. the answeres to your questions are as follows:<br /><br />Did you replace both upper and lower crank shaft seals with the rebuild?? <br />Yes<br /><br />Could you have a leaking fuel pump diaphram sucking extra fuel into the top cylinder??<br />Thanks for that one, I never thought it was possible. I'll have to check it out.<br /><br />The carb is common to both cylinders but the reeds are not. Did you do the dollar bill test to look for 'back puffing' of the carb?? <br />Again, please pardon my ignorance, but could you explain the dollar bill test?<br /><br />Do both plugs look the same??<br />Yes<br /><br />I don't think I mentioned it before, but I also replaced the reed plate, but used the old reeds and backers. However they looked fine under a 20x lupe and met the specs of .010" gap -<br />centered according to the book.