spark test results

[jeff6898]

1979 Evinrude 85hp 85999R

Going though trouble shooting and discovered this
If I keep all 4 plugs in remove the wires and hook them up to the spark plug tester I got good spark all 4, when I remove all 4 plugs and redo the test I once again loose spark on bottem left good spark other 3 any ideas?

 

[Joe Reeves]

Re: spark test results

Are you sure of that? It should be just the opposite. The spark test is always performed with the spark plugs removd in order to obtain the highest rpm cranking speed.

THe engine must be turning over at least 300 rpm in order for the ignition to function properly.

Normally, with the spark plugs installed, not all of the plugs may fire when cranking but as soon as one does fire, the rpms increase immediately which energizes the ignition to its fullest capacity resulting in having ignition/spark to all of the plugs.

The spark should be a hot strong blue lightning like flame, a real SNAP! Is it?