mercman, mercman.......?

Question

If the compression is ok at 85-95 in my 83 johnson 150, then why am I only getting half power at full throttle, I had a bad coil wire, which I changed all 6, thought that would fix the problem, but it did not. Should I go into the carbuerators next?

teh motor is running on all 6, it has sat up a little, a few months at a time, and yes the issue did come on suddenly, we were out all night it was fine, then at one point it just didnt sound right anymore. hasnt run the same since

Samson--- is the distributor on my outboard next to the muffler bearings or the blinker fluid

Answer 1

You had asked about your comp at 130. You have a crossflow V-6 and the 130 should be what you are seeing. Now, back in the 80's we went through the first way of ethanol blended fuels and we were installing low compression kits to make motors live. That may have been done. Or your comp gauge is off. Any way. even with that compression, you should still be running ok.
Did this issue come on suddenly? Has the motor been sitting up? Is it running on all 6 cyl? My lunch is almost over so it may take awhile before I respond to your answers. Gotta earn a living.

If it was running ok then went that quick, either you had a ignition failure or got some water in the carbs. Lets find out. In front of the carbs is an air box, remove the fasteners that hold the black cover on. Next remove the 6 bolt that hold the metal part to the carbs. Now you should have the carbs right there. Next you will need a clean glass jar. Looking at the bottom of the top carb on either side you will see a screw, loosen one of them and place the jar under it and remove the screw to drain the carb. What in the jar? Water will settle to the bottom and you will see it. Is there any crap in it? Now remove the other screw from the other side. Look inside, can you see the brass jet? If not, take some carb cleaner a spray through the jet and it should come out the other side. Tell me what you have seen to this point.

In sansom defence, if we were talking of a Mercury 150 pre 1976, it would have had a distributor. Only the old Evinrude V-4's had distributors.

Answer 2

Before going into the carburators,

- Check the the distributor position. A good the timing is necessary.
- Ensure that there is no leakage under the carburators gasket and in the vacuum hoses.
- The choke throttle in the carburators may be too widely open.
- Use a gas treatment to try to clean the carburator spray nozzles (pilot/idle jet).

If no result, than go inside the carburator.

Answer 3

first and for most, check your fuel lines. i ignored this simple little fix and burnt up a motor. just because the bulb gets hard doesnt mean its flowing correctly, especially at speed. what happened with me is the sealing o-ring on the tank connector was floating around and would clog the line. wasted one motor and i learned a lesson