73 Johnson 115 wont fire at cranking speed

[ndanieltx]

Here we go..<br /><br />Reasonably charged strong battery.. Put spark light onto engine between plug and plug wire.. Crank crank crank.. NO SPARK!<br /><br />Put on jump cabled.. Crank crank crank SOME SPARK sometimes..<br /><br />Pull out all 4 spark plugs.. Ground plug with spark light on it.. CRANK CRANK CRANK plugs are firing even ones not well grounded are jumping<br /><br />Put plugs back into motor.. Leave spark light installed.. Pull jumper cables.. CRANKING once again and no spark whatsoever..<br /><br />Any guesses as to the problem? <br /><br />Thanks!<br />Nate

 

[clanton]

Re: 73 Johnson 115 wont fire at cranking speed

You need a fully charged battery. Did you just change the power pack, or other ignition parts? If you have a spark that will jump a 3/8 gap, blue color with a snapping sound, with all plugs out. None or not much spark with plugs in, the sensor gap is to large. WWW.Rapair.com sells plastic tool to gap sensor.

 

[Joe Reeves]

Re: 73 Johnson 115 wont fire at cranking speed

Donkey.... That engine must turn over at least 300 rpms at cranking speed to fire the ignition. Actually those rpms are needed in order for the flywheel magnets flying around the stator to develop the approximately 300 volts AC to energize the powerpack.<br /><br />In your case, with the plugs out, the rpm is there. However, with the plugs in, the compression is causing resistance to that rpm, dragging it down.<br /><br />Check all of the cable connections. They should be wrench or plier tight, not wing nut finger tight. Even is tight, they might have a tight but dirty corroded terminal end which would cause a voltage drop.<br /><br />If all of the cable connections are clean and tight, and the battery is perfect, the usual cause of the problem you mention is that the starter is failing for some reason and it simply cannot develop the necessary torque to crank the engine at the 300+ rpm figure, in which case, either rebuild or replace the electric starter.

 

[ndanieltx]

Re: 73 Johnson 115 wont fire at cranking speed

Ok here is what I have replaced:<br />Starter- Rebuilt..<br />Solenoid.. NEW<br />Battery: only 3 months old<br /><br />Fully charged I can get a little spark but not enough to get the engine to start unless I use Starter Fluid.<br />If I jump it off the spark light gets a lil brighter and it trys harder to start and sometimes does.<br /><br />If I pull out all the plugs and just crank it without a jump on the battery I get all the spark I want. Yes much higher cranking RPM..<br /><br />Checked all wireing, even ran new ground wire.<br /><br />Checked voltage at starter and solenoid with Multimeter.. Getting just over 13 volts..<br /><br />The sensor gap sounds like it unless perhap could it be the stator is just totally gone?