Maine Maineac
New member
So I have an 84 mercruiser 3.0 and anything over half throttle doesn't seem to increase power or speed. So this is a project i started in 2018. 84 Galaxy with a 3.0 mercruiser. The boat didn't run early last year with a burnt out pertronix ignition. I converted it to points as it was cheap and I wanted to make sure the motor was good. It ran but I had tons of issues with the points. So long story short I did replace it with a new pertronix. The boat had some other issues like bellows and gimbal bearing. I was finally able to get someone to replace them. The boat was hard to get running (carb etc) but finally I seem to have it running pretty well on the ear muffs. Idled good... good throttle response...
So today was the first time getting it on the water after the bellows etc were changed. I had a bear of a time getting it to start and idle. After a readjust of the fuel/ air ratio on the carb it seem to clear up and run good again. I cruised for a couple hours at slower speeds and it was running pretty good and better and better the more we ran it. On the way back to the dock I wanted to open it up.
It runs great. but it peaked out at 30mph. I noticed it would maintain that speed at half throttle or anything above. As in full throttle didn't increase speed or rpm any more than half throttle. It sounds great. Doesn't seem to be bogging. Playing with the trim made it Bob a lot but really didn't help the speed or rpm.
So up to this point i have replaced...or done..
*Fuel filter and added a water separator separate one.
*Cap and rotor
*pertronix ignition
*oil and filter
*Ignition timing
*gimbal bearing, Bellows, Aligned outdrive (done at a marine shop)
*lower unit oil
*Complete carb rebuild with a full kit. (It was bad and this made a huge difference.)
*Replaced all gas with fresh non ethanol gas
*Starter, Battery and cables (not that I believe it is related.)
*Fixed motor mount issue.
I am sure I am forgetting some stuff.
Like I mentioned it runs pretty good. I just notice the lack of speed and it doesn't help to throttle up to full. It does actuate the carb more. The cable seems to be adjusted and working right. It just doesn't seem to change anything
Anyone want to help me with a checklist of things to go over and double check?
Much appreciated
Maine Maineac
So today was the first time getting it on the water after the bellows etc were changed. I had a bear of a time getting it to start and idle. After a readjust of the fuel/ air ratio on the carb it seem to clear up and run good again. I cruised for a couple hours at slower speeds and it was running pretty good and better and better the more we ran it. On the way back to the dock I wanted to open it up.
It runs great. but it peaked out at 30mph. I noticed it would maintain that speed at half throttle or anything above. As in full throttle didn't increase speed or rpm any more than half throttle. It sounds great. Doesn't seem to be bogging. Playing with the trim made it Bob a lot but really didn't help the speed or rpm.
So up to this point i have replaced...or done..
*Fuel filter and added a water separator separate one.
*Cap and rotor
*pertronix ignition
*oil and filter
*Ignition timing
*gimbal bearing, Bellows, Aligned outdrive (done at a marine shop)
*lower unit oil
*Complete carb rebuild with a full kit. (It was bad and this made a huge difference.)
*Replaced all gas with fresh non ethanol gas
*Starter, Battery and cables (not that I believe it is related.)
*Fixed motor mount issue.
I am sure I am forgetting some stuff.
Like I mentioned it runs pretty good. I just notice the lack of speed and it doesn't help to throttle up to full. It does actuate the carb more. The cable seems to be adjusted and working right. It just doesn't seem to change anything
Anyone want to help me with a checklist of things to go over and double check?
Much appreciated
Maine Maineac
