1981 Mercury 115 inline hole shot problem after idling

[realfastbug]

I have a problem with the engine loading up if I idle for too long like while a skier is getting ready for too long. If we are cruising around from 20 -40 mph then stop and idle for a second then hammer it then it seems ok with a slight hesitation. However if we hammer it after idling for too long it will kill the motor if you hammer it to pull a skier up.
Some background, I am pretty new to boats but handy in the way of cars. I just got this boat and the guy said he rebuilt the carbs. I found the timing to be way out of adjustment so I set that up the other day and have the carbs adjusted at 1 or 1.5 turns out. I also noticed the priming bulb has a pinhole on the engine side of it (I bought a new one but haven't installed yet). I also checked the compression and they are all between 105 and 110. My first plan to try adjusting the idle screws at the lake next time we are out. Any other suggestions? do you think this is a loading up of fuel issue too?
Thanks

 

[realfastbug]

Re: 1981 Mercury 115 inline hole shot problem after idling

I just read through the FAQ again and one question came up, when setting the timing with the throttle in the idle position are you setting it to 4-6 deg BTDC or ATDC? I used the clumer manual and it said to set it to table 12 primary something or other and that line said BTDC but I did see another setting mentioned at ATDC(retarded more) if this is the case it looks like my timing will need more attention, no problem I guess I have to take the boat out again

 

[Laddies]

Re: 1981 Mercury 115 inline hole shot problem after idling

It sounds like the idle mixture is to lean

 

[Chris1956]

Re: 1981 Mercury 115 inline hole shot problem after idling

Bug, A pinhole in the fuel pump diagham allows raw fuel into the crancase and will foul a cylinder or two. Could easily be the source of your problem. Be sure an fix it, and retest. If the motor still "loads" up at idle, likely the carb floats are defective or incorrectly set, or the idle mixture is set too rich. You can lean them a bit, but turning the idle mixture screw in 1/8 turn, one carb at a time and then go high speed and retest. Start with bottom carb and work up. If you lose the hole shot, that carb is too lean and you need to richen it 1/8 turn.

BTW - Idle timing must be 4-6 BTDC, when distributor arm just touches carb arm. Whne you set the idle speed, the timing may retard to ATDC.

 

[Chris1956]

Re: 1981 Mercury 115 inline hole shot problem after idling

Sorry about that, you don't have a dissy. Idle timing must be 4-6 degrees BTDC when timing arm just touches the carb arm.....