87 dt150 serious bogging problem

This is the max motor able to put on this boat, max weight is 6 people or 650 lbs. The motor was in shop last year getting full tune up spark plugsand wires , carb cleaning, impeler and housing, lower unit oil and inspection , thermostats etc...cost me over 750$$. I took it out this year it was great hole shot top speed of about 46 mph, then it all started , one day it just started bogging down one time it just wouldn't go over 2000 rpm, and sometimes just sputters. ive tried ringfree additive new oil, water absorber in fuel tank new gas, checked fuel lines, now sometimes it works good reaching rpms of about 4400 is that normal when i rev in nuetral i think it goes to about 6000. does weight make an issue, had about 580 lbs in there, but picked up third guy at launch ran good as hell but on the way back same amount of weight, it wouldn't even reach plane, but when they got in the front it hit plane in a few seconds and took off, it;s on a 18ft fish and ski stratos. thanks for your help

Re: 87 dt150 serious bogging problem

I have a 1986 150SS on a 1987 stratos 189FS that started bogging at around 4000rpm. I to went through the carbs, checked all gas lines for leaks (where it could suck in air at high rpm), re-checked the carbs and made sure the air vent on top of each carb was clear. There was nothing apparent so I changed the plugs and that fixed it. Now I am back up to 5300rpm and 61mph (according to the speedo).
Yes, weight does make a difference but your problem will be predictable, running good when empty and laboring when really loaded.
Have you pulled the plugs and looked into each cylinder to see the color (black and wet, gray and wet around the edges), You can take the plugs to an auto shop and they can check to see if they are firing or not. I put mine in my motorcycle and two of them would not fire even though they looked good. So, look again at ALL gas lines including the pick-up in the tank. The strainer screen on the bottom could be plugged. You could have stuff in your tank that pulgs the pick-up tube then clears itself and the boat is shaken around.
Good luck,
Jim