Here's a tip:

 

Well, no.

Edited April 18, 20178 yr by 240260280

I bought these by the case for my Mercury 2.5 outboard. We called them "gap-less plugs". 

Could be they were just fouled.  Four of them worked.  Once they foul and misfire a few times, the carbon paths get baked on, and you're kind of cooked unless you clean them or replace them.  Might not be the type or quality of plug at all.

I've wasted lots of troubleshooting time myself, in the past, when a simple tuneup, with new plugs, ended up fixing the problem.

i hadn't though of ohming the plugs. ill check them just for grins and post the results. my friend did mention something about increased resistance with the "fine wire" type of plug