2002 merc. doent want to get up on plane.

[Keith w]

I am having problems with my 2002 mercury efi not wanting to get up on plane. Carried it to mercury shop, they couldnt find anything wrong. After installing new plugs motor runs good for about 3 days. Then doesn't want to get up on plane. If and when it does it only turns about 5000 rpms. Then at ramp it will not push it on trailer. When this first started last year there was no miss noticeable. Now there is a noticeable miss only when trying to load boat on trailer. I have found no issues with fuel lines bubble or filter no trash or water in system. When it acts up I can change plugs and bam problem solved for 3 trips to lake. Then its same thing all over again. Running ql77c plugs. Any help appreciated.

[rock]

Welcome to the site. What do the plugs look like when you change them.

Rock

[Keith w]

Rock;
The top 4 plugs look clean. The bottom 2 are always more browned as far as the ceramic part is concerned. And seems to be more sunburned fuel mixture on the bottom 2 plugs

[All9up]

I would try hotter plugs like an NGK BU8H

[BOATMANBLUES]

just went through this with a 3.0 efi...ended up being one bad cdm...all 6 would fire on a spark check...pulled all primarys and checked individually and one would not fire...

[Keith w]

I ran a set of them. Still same issues. Thanks tho.

[Keith w]

I ran a set of them for a while still same issues

[Keith w]

I will tell tis to the mechanic when it goes back to the shop. Thanks for the information