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Dan Bernard

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1999 Johnson 40 HP no spark when cranking at 800 RPM with spark plugs in motor, take Plugs out and motor cranking at 1500 RPM I have good spark? had done some testing on the stator found it to be bad , replaced stator ,timer base and power pack . still no spark while cranking with plugs in it at 800 RPM take plugs out and crank it at 1500 RPM and good spark ??? HELP ??
 
Make sure bracket that holds power pack is grounded to block. Remove spark plugs,remove black/yellow wire from power pack plug,ckeck for spark ann respond!
 
Rwbutler said:
Make sure bracket that holds power pack is grounded to block. Remove spark plugs,remove black/yellow wire from power pack plug,ckeck for spark ann respond!
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Bracket is grounded and black/yellow wire disconnected . plugs in 800 rpm no spark plugs out 1500 rpm good spark ??
 
Your symptoms are classic for a bad stator or slow cranking. You already replaced the stator, so rule that out. That leaves slow cranking. 800/1500 sounds unbelievable to me. Are you sure about those numbers?
 
using the boat tach . and yes it has a deadmans switch but disconnecting black/yellow wire should by pass that.. my question is why do i have good spark at 1500 rpm and not at 800 rpm ???
 
Dan Bernard said:
using the boat tach . and yes it has a deadmans switch but disconnecting black/yellow wire should by pass that.. my question is why do i have good spark at 1500 rpm and not at 800 rpm ???
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Because the stator coils generate electricity as the flywheel magnets pass by. The faster the magnets pass by, the more electricity is generated. 800/1500 is faster than the dang thing runs (at idle) after it does start. 200 RPM is generally considered minimum for starting.
 
fdrgator said:
Because the stator coils generate electricity as the flywheel magnets pass by. The faster the magnets pass by, the more electricity is generated. 800/1500 is faster than the dang thing runs (at idle) after it does start. 200 RPM is generally considered minimum for starting.
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I realize that that's what I don't understand why I have to take the plugs out to get it to spin real fast to get spark when 250 rpm should be enough to produce enough voltage to run the ign system , and yes the tach is working this motor is spinning it's ass off (lol) to get enough voltage to run the system . now when I said I replaced the stator I got one used , but said to be good . same problem as I had with my old stator that's why I thought my stator was bad but same results
 
You have to confirm your tachometer is reading correctly.------ as I agree----1500 RPM is doubtful cranking speed !----Replacing parts based on guessing gets expensive.-----Do you have any meters to check electrical values , yes or no ?----Have you considered taking the starter apart for inspection ?------Time to do some real and meaningful trouble shooting I say.
 
I have done electric trouble shooting on the engine . using the fluke DVOM . and the Johnson no start troubleshooting flow chart . auto tech for the past 45 years . have had this boat 4 years now . one day ran fine next day wouldn't start . found the orange and orange/black wires were open when doing a ohm resistance test. when I got the other stator both brn brn/yellow orange orange/blk resistance test were ok . but the eng will crank at 1500 rpm WITH the plugs OUT and that is the only time i get spark
 
Dan Bernard said:
I have done electric trouble shooting on the engine . using the fluke DVOM . and the Johnson no start troubleshooting flow chart . auto tech for the past 45 years . have had this boat 4 years now . one day ran fine next day wouldn't start . found the orange and orange/black wires were open when doing a ohm resistance test. when I got the other stator both brn brn/yellow orange orange/blk resistance test were ok . but the eng will crank at 1500 rpm WITH the plugs OUT and that is the only time i get spark
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Does your fluke have DC Amps capability, suitable for 5 Amps? If you want to know the actual current flowing to the battery, that is the way to do it. Connect the instrument in series with the red wire.
 
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