1989 100 hp Mercury won't idle

[murraymtn]

Howdy all,
I have a 1989 100 hp Mercury that I can't get to idle. I cleaned all the carbs. New power pack, great spark, rebuilt the fuel pump. Checked all vacuum lines for leaks. The engine fires right up but will only run if I keep pushing the choke. As long as I keep choking it with the key I can throttle the engine and get it to rev up. As soon I quit choking the egine it will idle for about 10 seconds and dies. Heelllllpppp!!! thanks
John

 

[achris]

Re: 1989 100 hp Mercury won't idle

You are aware that these engines only idle on 2 carbs.... If you didn't put them back where they came from you will have problems... If you did, then check the idle mixture screws... Sounds like it's running too lean...

Chris........

 

[murraymtn]

Re: 1989 100 hp Mercury won't idle

Thanks, yes I bought a manual and learned all about the 2+2. I have turned the idle mixture screws out as much as 4 turns and get no response. One thing I did do was eliminate the automatic oil mix system. I mix my gas in the thank. Would this affect anything ?

 

[murraymtn]

Re: 1989 100 hp Mercury won't idle

Ok folks. I have done a few more things. I pulled the fuel line off the fuel pump on the output side. Cranked the engine over 15 times and fuel pulsated
nicely out of the pump. So I know the carbs are getting gas. I have narrowed it down to a vacuum leak. I am going to check compression and for vacuum leaks. Does anyone know if the fuel enricher could cause a vacuum leak? thanks John

 

[OutboardProject]

Re: 1989 100 hp Mercury won't idle

I have a 1990 Mercury 100hp 2+2 setup that would pop and die at idle. I tried fuel pump rebuild, new plugs, adjusting carbs per Clymer Manual, but nothing worked. Turned out the gaskets between the carbs and the reed cages and cages and intakes were leaking resulting in excessively lean mixture at idle. $50 worth of gaskets, some time wrenching and problem solved. Engine runs great now! Look up the parts diagram and you will see all the gaskets and plates needed. Good luck.