50 HP Mercury Idle Problems

[sfryz]

I recently purchased a boat with a 1965/66 Kiekhaefer 50 HP Mercury 2-stroke (4cyl 2 carbs) motor (serial# 1857704). The boat had been sitting for about a year so I cleaned out the carbs with carb cleaner and the engine was running fine in the tank.<br /><br />When I took the boat out on the water I couldn't get the motor to idle unles the "warm start" lever was used. The engine worked fine in warm start and at top speed but would not go down to idle without stalling.<br /><br />I am using premium gas with a 50:1 fuel mixture and I have the main mixture screws turned out a 1/2 turn. <br /><br />I tried cleaning out the carbs again and it seems like the carbs are getting either too much or not enough gas. Not sure where the problem could be.<br /><br />Any help would be appreciated.

 

[12Footer]

Re: 50 HP Mercury Idle Problems

First, compession check.If the compression is good, it might be running too lean. you may have to get someone to go with you as pilot, while you adjust the carbs underway. But give it a good decarb treatment first. After that,get the engine warmed-up,fast idle, and turn out each carb's mixture one-eigth turn (counter clockwise),and wait 20seconds , to reach the results of the adjustment. if it doesn't stumble, do another one-eighth turn out on each carb and wait. do this until the engine just starts to run rough. Then, turn them both in one-eighth turn until it just smooths out. It will be very close to right, but may be a bit rich. But being rich is far better than being lean, on a 2cycle engine.<br />If you can't get it to idle after that, you may have a defective fuel pump.