3.0 Choke plate

[sat1962]

I was reading a thread last night and I believe Don said the way to test it is to turn the key on and see if it stays closed or opens. Mine seems to stay closed......what can I do to repair or correct this. I just rebuilt this carburettor ( 1987 mercruiser 2 barrel 130 hp ) and I have a couple of questions....

What causes the flapper to open up on the carb when you accelerate....is it vacuum or is it mechanical with linkage?

I pulled my spark plugs..they were brand new last time I was on the lake. They were sooty and wet leading me to believe it is still running rich. WOT 3800-4000 according to tachometer, prop is 14x19, planes fine, top speed on a 19ft Glastron is between 30-35 mph. Will sometimes idle rough and sometimes it is hard to start even with engine warm.

Any advice greatly appreciated. Thanks

 

[sat1962]

Re: 3.0 Choke plate

btw.....my wife doesn't want me to poke around too much with it, i.e not at all, as it gets us out on the lake and back to shore without assistance unlike some other boats we have had in the past!!

 

[Fishermark]

Re: 3.0 Choke plate

You might have a mechanical choke or an electrical choke. If electrical, then yes, with the key on it should start to open. (Both actually work the same way - a bi-electric element/spring is heated and that causes the choke plate to open. In the mechanical choke, the heat comes from a "pipe" from the engine - in an electrical choke, the heat comes from a heating element).

 

[sat1962]

Re: 3.0 Choke plate

Thanks for the reply i have an electric choke. How can I tell if its working properly and does this choke plate open all the way at full acceleration ?

 

[imported_TheMan]

Re: 3.0 Choke plate

If you read the manual for setting up the carb, you are supposed to bend the choke rod so the plate is open 0.080 or so when it is cold. When the engine is warm, the choke plate should be fully open.. It lalso tells you where to align the tick marks on the electric choke housing (2 ticks lean I believe).

Do you have a manual? There is an on-line copy you can probably use since I think carb models are pretty much the same thorughout the years.

 

[sat1962]

Re: 3.0 Choke plate

Okay i adjusted the electric choke one notch towards lean as manual suggests .On to my other issue low wot rpm 3800.I checked points cap and rotor looked good i checked anti siphon ball looked good.Then at idle on muffs in driveway i checked timing it was at 2 degrees btdc i set it at 6 degrees btdc as manual calls for.Now true test will be saturday on water.Would the timing off like that make it not reach suggested 4200-4600 rpm ? Thanks to all for the advice and suggestions.