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77 25hp lacks spark how do i check the power pack?

B

bill VV

New member
HELLO.

My 1977 25HP manual start w/CDII ignition has been increasingly difficult to start until last week when it totally refused. After checking the obvious I found no spark. I used my multimeter to perform the first 8 tests per Seloc but I do not have M8 or S8 tester to proceed. On advice of a backyard mechanic I used my meter and found the charge coil generating 30 to 35V and the sensor 0.2 to o.25V. Is this sufficient and if so how do I check the power pack or do I assume it is bad and put in new?

5 Yrs ago I had similar problem (although it would start eventually] and I replaced 2 ignition coils, power coil, sensor coil and then the power pack as I still had no spark. Worked exceedingly well till recently. Both ignition coil covers were cracked then but the replacements are in spec. per Seloc tests. The engine is old and pistons scored but I have 100 compression and am trying to keep costs down so if I need it I will have some cash for a new engine. HELP
 
The M8 and S8 are obsolete, as are the test procedures listed in the manual. Furthermore, you cannot test those voltages with an ordinary multimeter. You need a DVA meter or adapter (peak reading voltmeter). How to do it is here: http://issuu.com/cdielectronics/docs/troubleshootingguide?e=2044661/2010855

BTW, the most common cause of complete loss of spark on both cylinders is a shorted kill circuit (black/yellow wire). Disconnect it and see if you get spark.
 
fdrgato.

Thanks for quick response. I have tried sending this earlier but guess it never went thru. I cannot find the right meter to check for power coil output w/o mail ordering and can't justify the cost for a 1 time use as I'm soon to be 80. Since I read 30-35 V ac with my regular V meter it seems the power coil works but may not put out enough voltage for the power pack to function. In thinking about it I think that a correlation could be made as to probable range for the voltage if using a DCA meter. This may just amplify my ignorance of electricity but would think there would be a simple formula like 35X???=actual AC voltage to the PP (or at least in the ball park). Incidently, how many volts must reach the PP for it to work?

I have checked the kill switch at least 8 times and am sure it works properly. I have checked and cleaned all connections outside the flywheel including
the condition of the wires. I have checked all coils for shorts and resistance and they are in spec per Seloc. If I don't receive any possible solutions I will pull the flywheel for inspection. I very much appreciate your help.
 
kimcrwbr1 said:
sorry I read further and radio shack dont carry a 400 volt capacitor that works better for the higher voltage spikes. The capacitor will charge up real fast one or two pulls on the rope
Click to expand...

You don't need such a large capacitor. I made up such a rig using only 0.2mfd 450V and it works just fine.
 
30-35VAC does sound low, but that is guesswork, little better than no test. You are not dealing with an AC sine wave, but short pulses with lots of space between. There is no conversion formula. Make yourself a DVA adapter if you don't want to invest in a "real" meter.
 
Thanks guys. Your comments are greatly appreciated. The site you gave me has a DC adapter for $26+ and that is ok w/me. Might even go the make your own route. Thanks again. Great to connect w/people knowledgeable and willing to pass it on. Bill VV
 
Dear fdrgator.
I have been to Radio Shack. No capacitator to 400 v and said they could not order one. Are they putting me on because they know I may not be a regular and this would be a minor order? No other place n town handles this stuff. Thanks. Bill
 
Hi Guys.
UPDATE>My neighbor had a Power Pack from an old motor he junked and now I have good spark. Have not run the engine as I am working on H2O P. and lower unit. Thanks again for your comments as they helped a lot. Bill VV
 
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