Spark tester

[bbx2]

This is going to sound goofy! I have Mercury 8 prong spark tester that I use all the time. My friend has '95 150 Evenrude that he wanted to check spark from his coils. We checked using this gage and no fire. After working on it for hours we took the boat to a shop,they found two plug wires bad.Replaced them and had fire on all wires and it started fine.Brought home and checked with Mercury spark tester NOTHING.We checked the continuity from where the clamp attached to the motor back to the pin and there was continuity there. I came home put it on my 9.9 Mercury and it showed spark!!! Does anyone know what is going on here.

 

[oldman570]

Re: Spark tester

Different motor manufacture and not all ignitions systems will jump the gap of the tester mote than likely. The gap setting of the tester may be to wide for that system. JMO
Oldman570

 

[eggs712]

Re: Spark tester

Good answer above. I would get yourself an adjustable spark tester from an auto store; they're less than $10.

Something like this: Great Neck/Adjustable ignition spark tester (25069) | Ignition Tester | AutoZone.com

 

[racerone]

Re: Spark tester

Most CDI ignition systems fire a spark across a gap of up to 1/2" or more.----That is the proper test.