1969 2 Stroke Mercury 65HP starts, idles, and runs smoothly, only reaches 5mph.

[3ncore1234]

For starters, I know pretty much nothing about boats, so my apologies for my complete incompetence.


Anyways, I picked up a boat over the weekend that came with a 65HP 1969 Mercury 2 stroke engine. The owner said that when he last had it out on the lake in August the motor ran great and he was able to get it up to 25 or so. From what I can tell, this boat was sitting for about 10 months. Now, I know absolutely nothing about boats, so my apologies if I broke like 800 rules about owning a boat here. I bought the boat and took it out the next day. We did absolutely nothing to the boat expect for putting in a 50/1 gas/oil mix. It started up great, and we had it running for about 30 minutes. However, we could not get the boat to go above 6-7mph even at full throttle. The RPM seems to not crank up to anything close to where it should. I'm just wondering where I should start and what I should have probably done with a boat that was sitting for 10 months before taking it out on the water. Once again, I apologize for being an idiot but I would like to try to learn about these things.

Thanks!

 

[racerone]

Sounds like you might have one plugged carburetor.----Are both throttle plates opening fully ?-----No fuel going into 2 cylinders means no oil either !------Not good for the motor.------Here is what I would do.----Do a compression test first.----Then check to see if you have strong spark on all 4 leads.------If those are good then you need to look at the carburetors and fuel pump.

 

[3ncore1234]

Sounds like you might have one plugged carburetor.----Are both throttle plates opening fully ?-----No fuel going into 2 cylinders means no oil either !------Not good for the motor.------Here is what I would do.----Do a compression test first.----Then check to see if you have strong spark on all 4 leads.------If those are good then you need to look at the carburetors and fuel pump.

Thanks for your reply. I really appreciate it. I'm not sure if both throttle plates are opening fully, and I'm not really sure how to check that. I will run a compression test next weekend when I can get back to the boat and work on it. I'll also check if the leads have good spark. I literally know nothing about how to work on boat motors, but I think I should be able to run a compression test and check the leads. If the carburetor is plugged, is there an easy way to unplug it without going through a complete rebuild? Thanks again for answering me, I'm just a little clueless with these things.

 

[racerone]

Time to find a manual or be prepared to pay huge $$$ at a shop.