84 70hp won't idle

[kh0432]

Took my project boat out for the first time today and it didn't go well. First, a brief history. Bought the boat knowing that it wouldn't idle. The owner said he never found the time to try and fix it. What I did so far is, overhauled all 3 carburetors, found 1 was missing the idle jet and 1 had a piece of dirt clogging it. The fuel pump had a broken reed and I replaced the pump. The primer solenoid was disconnected because the lever was broken off. Replaced the lever and reconnected the hoses. The vent valve on the built in tank was closed with mud from some insect. Replaced the vent valve. One cylinder wasn't firing due to a bad wire connection, fixed that. It seemed to be ready running in a test tank so I took it out today. Had a hard time getting it to stay running at the pier but finally got up on plane and it ran like a stripped ape for about 2 minutes, then died like it ran out of gas. The primer bulb was soft and after pumping it till hard the motor would start and run when given gas but wouldn't idle. Got it back to the dock but when I reduced speed I would have to keep bumping the primer solenoid to keep it running. also, when I got back to the dock, the temperature alarm went off but I could touch he heads and they didn't seem hot. Impeller and thermostat have been replaced and I have a strong flow out of the pee hose. Could running a lean mixture cause it to overheat? I got home and noticed that when I squeezed the primer bulb I could hear a noise in the built in gas tank like a restriction. I hooked an electric fuel pump to the hose to see how much gas I could draw through it and it wasn't much. I removed the anti siphon valve from the tank and the flow seemed to be much better. Motor started fine but I still have to bump the primer solenoid to keep it idling. Can rev it with no problem. I noticed in the center of the carburetors there is a tube in front of the butterfly and droplets of gas are coming from them. I assume its for off idle speeds and I may have the idle screws in too far. I'm confidant that all the idle passages are clear in the carburetors. It acts like it has a vacuum leak but I don't know where it could be and I'm not too familiar with 2 stroke motors. Thanks for any help, Keith

[boats.net]

Does sound like fuel issue, start your idle/air screw and 1.5 turns out then adjust from there. The overheating issue is not likely associated with the lean condition. If you take silicone spray and spray around the motor if rpm changes then that would be where you leak is.

[kh0432]

thanks for the suggestion to spray to find the leak. I think the fuel supply problem is corrected. These carburetors do not have any adjustments. Thanks, Keith

[kh0432]

70 hp won't idle

Checked the compression today and the readings were top cyl 90, middle 110, bottom 70. This was with engine warm and carbs fully open. Thinking of pulling intake off to inspect reed boxes and gaskets and pulling the cylinder head off to check gaskets and cylinders before pulling the power head for a rebuild. I tried the trick from the Selock repair manual to check the reed valves. It says to place a card 2 inched in front of the carb when running and you should only get a slight mist on the card if the valves are good. If the card gets wet with gas, there is a broken reed. The card was dry and I noticed it flexed in and out the same amount on each cylinder. The spark plugs from the 2 low cylinders seems to be a little wet compared to the good one. Thanks for any help. Keith