Home › Forum › Ask A Member › 1974 Evinrude 9.9 won’t idle at low RPMs, need help › Re: 1974 Evinrude 9.9 won’t idle at low RPMs, need help
April 24, 2016 at 7:14 pm
#35407
The UL-81J is a booster gap plug. That is, the spark jumps a gap within the plug before getting to and jumping the gap at the tip. That forces the voltage up, which helps it to fire a fouled plug. I’m not familiar with the NKG’s, so not going to make a comment or choice there. Matter of fact, I don’t have up-to-date experience on those engines at all. Other guys here do. But an awful lot of these grey hairs were gotten while trying to make them run back in "the day".