1994 Mercury 115hp fast idle questions

[Maddoxsdaddy]

I posted this a couple weeks ago with no response so i'll try again... especially because i'm trying to sell the boat and i have a conscience and am unwilling to screw a potential buyer.

I have a 1995 Astro w/a 1994 Merc 115. I just finished a complete fuel system rebuild including replacing 1 carb, rebuilding the 3 others, new lines, new fuel filter, new line from the tank to the motor and rebuilt the fuel pump. During the tear down/rebuild phase of the project, i am certain that i didn't adjust any of the linkages, idle set screws, or throttle cable. Now, the motor won't idle less than 1400 rpm. What could i have missed? I've haven't tried re-setting the idle screw because i didn't mess with it when i took the carbs off (why would i need to change it?). I've pulled the carbs loose, checked the gaskets and re tightened but still have the same racing idle. Maybe i put a pinhole in one of the many lines or didn't get the gaskets in the fuel pump set right? Any suggestions?

Thanks,
TB

 

[Dave1027]

Re: 1994 Mercury 115hp fast idle questions

The first thing to check is that you ordered the correct parts. The bottom two carbs should not have idle screws. The top two should.

Next is I find it very hard to believe you can remove the carbs and put them back on without having to verify some sync and link things afterward. First thing is to take off the front airbox cover and make sure all of the carbs are closed completely in the idle position.

 

[Maddoxsdaddy]

Re: 1994 Mercury 115hp fast idle questions

Appropriate parts were ordered from a very reputable service dealer in the area. The carbs all have quick disconnect ball fittings that just pop off without having to adjust or move anything out of the ordinary. I will check to see if all butterflies are closed at idle. The motor actually idles fine until it warms up then it speeds up.

 

[achris]

Re: 1994 Mercury 115hp fast idle questions

Not all the carbs are the same. If you got a couple mixed up then you could end up with the problem you have. And apart from the presence or absence of an idle mixture screw they look identical.

Check that the top 2 carbs have idle mixture screws and the bottom 2 do not have idle mixture screws.

Chris.........