Better idle on a Johnson??

[Diablo Dan]

I am a Merc guy, my co-worker has a '91 150 on his new to him bass boat and the idle quality is not great.
It is a tad hard to start, runs rough etc.
I want to enrichen the mixture.

Do I need to re-jet or is there an idle mixture screw somewhere?

Any reccomendations shy of cutting it off and putting something black back there? :p

Thanks for any advice.

Dan

[sixpac]

is this a fast strike 60 degree motor?, or a 90 degree!

[Diablo Dan]

He says that it is a GT 150.

I replaced the lowerest carb's float bowl due to a crack. We had to replace the jets due to them being a different for aluminum and plastic bowls.

We did not run the motor prior to replacing the bowl because of the fuel leak.

Spark and compression were ok.

Dan

[sixpac]

i dont think there are any idle mixture adj screews!

to increase the idle mixture [ richen ] replace the idle jets with smaller jet #'s.

[Forkin' Crazy]

The carbs are probably stopped up on one of the passage ways, jets, etc. Give them a good cleaning. If you start changing stuff, it may make it worse.

[bigbore]

The idle,air bleeds are adjustable from 93-up.Its the large flat blade,1\8 turn (clockwise)richens n 1\8th turn is substantial.

[EMDSAPMGR]

You might decarb the engine and see if the idle improves. Also, check the recirc system. When the valves quit working, it can affect the idle. Those engines have a history of the plastic float bowls warping and leaking fuel into the lower cowl. If you replaced one, you might want to do the other.