97 Mercury 150 efi

[Jgwentworth]

Hello, I have a 1997 mercury 150 efi that I just picked up. At idling and rpm below 800 and from roughly 1000-1500 rpm the engine shakes quite rough. It doesn’t have any problems with the hole-shot and is fine at high rpm’s. I changed the plugs and this got rid of the issue. I put about 4 hours of mostly idling on the plugs and the issue returned. I did have bouts of wot in between idling. I’ve attached pictures of what the plugs look like. Is this a known issue or am I getting too much oil/fuel?

 

[Dukedog]

do you have any information on injector health?.. as in recent flow tested and cleaning?.. o-rings, tip screens and such?.. justa a start of several things it COULD be...

if you would like send me an email addy and i'll send ya an OEM manual (pdf file) for it......

 

[Jgwentworth]

No I don’t have any information on that. Tried taking the boat in, but it just sat for 3 weeks because they were busy. Just trying to potentially fix it myself. I do have a manual already, thank you.