Read my plugs

[Dave1027]

This is from my '88 Merc 100hp 4 cyl 2+2.



These are laid left to right in sequence cyl 1 thru 4. What's wrong with number 2? I'm guessing the number two carb is running too rich?

 

[Faztbullet]

Re: Read my plugs

Carb flooding due to float level or inlet needle, weak spark at low speed causing incomplete combustion, defective bia's in switchbox causing plug to fire late or high resistance in plug.......

 

[Dave1027]

Re: Read my plugs

Carb flooding due to float level or inlet needle, weak spark at low speed causing incomplete combustion, defective bia's in switchbox causing plug to fire late or high resistance in plug.......

Awesome analysis. Thanks.

 

[bmartin]

Re: Read my plugs

Hi, I have a 96 of the same motor and am wondering why yours has gappless plugs?

 

[Charlie61]

Re: Read my plugs

I have a 1983 115 inlin6 that uses gappless plugs it's what the manual called for ! maybe you could check your manual of ask one of the boat part supplyers about your!

Hi, I have a 96 of the same motor and am wondering why yours has gappless plugs?

 

[Dave1027]

Re: Read my plugs

Hi, I have a 96 of the same motor and am wondering why yours has gappless plugs?

It's because I have an '88 which was the first year for that motor. It was before Merc received complaints about the bottom two cylinders kicking in. Basically, the kicking in is felt much more with the gapless plugs. The gapped plugs helps to smooth the transistion. I tried them on the suggestion of a marine mechanic and did not like them. The engine is just snappier with the gapless. I don't know exactly why that is.

You could run the gapless too if you wanted to. It takes NGK BUHW. Just don't spend a lot of time in the 1800 rpm range or it's jerky as hell. I don't normally use that rpm any way. All you are doing is pushing water. You need about 3000 rpm to get on plane.